Amphiphilic diblock copolymers based on methoxy polyethylene glycol (MePEG), 1, 6-hexanediol and maleic anhydride with different molar composition were synthesized by solution polycondensation. Self-assemble behavior of amphiphilic diblock copolymer in different solvents by dialyzing technique was discussed. The micelle morphologhy was observed by TEM. It was found that well core-shell MePEG1900/Polyester 2162 copolymer nanoparticles can be formed by self-assemble in acetone solution. In addition, the size of nanospheres measured using dynamic light scattering exhibited a narrow monodisphere size distribution and an average diameter in the ranger of less than 200nm.