This paper proposes a JPEG image compression technique based on all phase inverse discrete cosine biorthogonal transform(APIDCBT).The APIDCBT matrix is a new form of transform matrix.This paper demonstrates its expression and proposes the definitions of biorthogonal transform and dual biorthogonal base vector.This transform algorithm saves the operation time due to without quantization.It can get the same compressed result and even better performance in the case of low bit rate compared with DCT.