Abstract: The photoinjected energy recovery LINAC (PERL) is a product of two basic techniques: the photoinjector and the superconducting energy recovery linac. Its major performances is to get the high brightness and high average power electron beams, operating for CW, and there are good application vistas in the high radiation field, include high average power FEL and new generation light sources. The photoinjector is the best source for the production of highbrightness electron beams. The superconducting energy recovery linac can deliver nonstored intensecurrent electron beams. This paper presents a preliminary study on the DC gun photoinjector and the superconducting cavity linac. When the DC high voltage is greater than or equal to 1MV and the accelerating field is greater than or