We propose a scheme to form a combinative triple-well optical trap for cold atoms or molecules in focus plane by using an optical system composed of a lens and a phase-type spatial light modulator (SLM) based on liquid crystal microdisplays illuminated by a plane light wave. The principle of forming a triple-well optical trap is analyzed and the characteristic parameters of optical potential are calculated. We also discuss the evolution between a tripe-well optical trap and a double-well one (or a single-well one). Additionally, the propotential applications of our triple-well trap and its novel optical lattices in four-wave mixing with matter waves, cold collision of three atomic species and so on, are explored.