A standing-wave cavity regenerative amplifier without Faraday rotator is demonstrated. In addition, according to the residual reflectivity of the thin film polarizer, the beams of injected seed laser and output regenerative amplified laser are separated. Finally, under a repetition frequency of 10 kHz, an amplified picosecond pulse laser output with an average power of 4.87 W is obtained, and the pulse width is 53 ps. Furthermore, the laser beam quality factor M² is smaller than 1.19.