Low-field magnetic susceptibility of the diluted magnetic semiconductors Zn1-xMnxSe was measured between 4.2 and 30 K for the Mn concentration range 0.1≤x≤0.50 using SQUID magnetometer. When x≥0.30, the system shows a spin-glass transition in the above temperature range, as evidenced by a somewhat rounded cusp in the susceptibility. The transition temperature of spin-glass is as follow: x=0.30, Tf=10.5 K; x=0.40, Tf=16.0 K; x=0.50, Tf=19.5 K. The phase diagrams for the boundary of the paramagnetic and the spin-glass phases are obtained for this system. The difference of spin-glass transition temperature between Zn1-xMnx Se and Cd1-xMnxSe is discussed. It is found that for any given Mn concentration x the spin-glass transition temperature Tf of Zn1-xMnxSe is higher than that of Cd1-xMnxSe.