Having a \gamma /\gamma′ microstructure similar to Ni-base superalloys and also including various alloying elements such as Al and W, new Co-base superalloy, namely Co-Al-W-base alloy, has been widely studied as a kind of potential alternative of Ni-base superalloy, which is the most important high-temperature structural material in industrial applications. Besides, Co-Al-W-base alloy has also excellent mechanical properties, for example, creep properties comparable to those of the first-generation Ni-base single crystal superalloys. In our previous work, the ideal composition formula of Ni-base superalloy has been obtained by applying the cluster-plus-glue-atom structure model of faced centered cubic solid solution, which shows that the most stable chemical short-range-order unit is composed of a nearest-neighbor cluster and three next-neighbor glue atoms. In this paper, the ideal cluster formula of Co-Al-W-base superalloy is addressed by using the same approach. Based on cluster-plus-glue-atom model theory, according to lattice constants and atom radii, calculations are carried out. The results show that the atom radius of Al is equal to Covalent radius (0.126 nm) and for \gamma′ phase the atom radius of W changes obviously (0.1316 nm). After analyzing atomic radii, the chemical formula for Co-Al-W ternary alloy is calculated to be Al-Co₁₂(Co,Al,W)₃, which signifies an Al centered atom and twelve Co nearest-neighbored cluster atoms plus three glue atoms, which is in good consistence with that for Ni-base single crystal superalloy. For multi-element alloy, the alloying elements are classified, according to the heat of mixing between the alloying elements and Co as well as partition behavior of alloying elements, as solvent elements-Co-like elements \overline \rmCo (Co, Ni, Ir, Ru, Cr, Fe, and Re) and solute elements-Al-like elements \overline \rmAl (Al, W, Mo, Ta, Ti, Nb, V, etc.). The solvent elements can be divided into two kinds according to partition behaves: \overline \rmCo ^\gamma (Cr, Fe, and Re) and \overline \rmCo ^\gamma′ (Ni, Ir, and Ru). The latter is further grouped into Al, \overline \rmW (W and Mo, which have weaker heat of mixing than Al-Co ) and \overline \rmTa (Ta, Ti, Nb, V, etc., which have stronger heat of mixing than Al-Co). Then all chemically complex Co-Al-W-base superalloys are simplified into \overline \rmCo \text- \overline \rmAl pseudo-binary or \overline \rmCo \text- \rmAl \text- \left( \overline \rmW,\overline \rmTa \right) pseudo-ternary system. Within the framework of the cluster-plus-glue-atom formulism and by analyzing the compositions of alloy, it is shown that the Co-Al-W-base superalloy satisfies the ideal formula \left \overline \rmAl \text- \overline \rmCo _12 \right\left( \overline \rmCo _1.0\overline \rmAl _2.0 \right) (or \left \rmAl \text- \overline \rmCo _12 \right\overline \rmCo _1.0\rmA\rml_0.5\left( \overline \rmW,\overline \rmTa \right)_1.5 = \overline \rmCo _81.250\rmA\rml_9.375\left( \overline \rmW,\overline \rmTa \right)_9.375 at.%). In the same way, those of \gamma and \gamma′ phases are respectively \left \overline \rmAl \text- \overline \rmCo _12 \right\left( \overline \rmCo _1.5\overline \rmAl _1.5 \right) (or \left \rmAl \text- \overline \rmCo _12 \right\overline \rmCo _1.5\rmA\rml_0.5\left( \overline \rmW,\overline \rmTa \right)_1.0 = \overline \rmCo _84.375\rmA\rml_9.375\left( \overline \rmW,\overline \rmTa \right)_6.250 at.%) and \left \overline \rmAl \text- \overline \rmCo _12 \right\left( \overline \rmCo _0.5\overline \rmAl _2.5 \right) (or \left \rmAl \text- \overline \rmCo _12 \right\overline \rmCo _0.5\rmA\rml_0.5\left( \overline \rmW,\overline \rmTa \right)_2.0 = \overline \rmCo _78.125\rmA\rml_9.375\left( \overline \rmW,\overline \rmTa \right)_12.500 at.%). For example, alloy Co₈₂Al₉W₉ and its \gamma and \gamma′ phases are formulated respectively as Al-Co₁₂Co_1.1Al_0.4W_1.4 (～ Al-Co₁₂Co_1.0Al_0.5W_1.5), Al-Co₁₂Co_1.6Al_0.4W_1.0 (～ Al-Co₁₂Co_1.5Al_0.5W_1.0), and Al-Co₁₂Co_0.3Al_0.5W_2.2 (～Al-Co₁₂Co_0.5Al_0.5W_2.0).