Poly (butyl acrylate-co-methyl methacrylate) copolymer microspheres were prepared by suspension polymerization method whose reactive systems were initiated with azobisisobutyronitrile, cross-linking agent of ethylene glycol dimethacrylate, and suspending agent of poly (vinyl alcohol). The factors of stirring speed and cross-linking agent on the copolymer microsphere conversion rate and particle morphology were investigated. The tunable copolymer microspheres were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermo-gravimetric analysis, and laser particle size analyzer. The results showed that the volume average particle size of copolymer microspheres was 100130m with narrow size distribution, and their degradation temperature was tuned to be much higher than that of the poly (methyl methacrylate), which may provide a candidate material for modifying fluid channels in oil formation.