In this paper, a double epitaxial and high energy implant (DEI) is proposed to improve the performance of charge collection and radiation hardness. Three-dimensional process procedure and physical level simulation are presented. The results show that the internal distributions of electric potential and electric field are improved; the seed point pixel collected charge increases about 70% and reduces the collected time to 64%. In addition, the DEI structure increases the collecting efficiency in a radiation range from 1012 to 1015 cm-2as compared with the standard monolithic active pixel sensors.