The advantage of optically pumped compact cesium clocks is that they have a higher utilization of atoms compared to traditional magnetic state?selection cesium clocks. The group in Peking University has made breakthroughs in the frequency stability of optically pumped compact cesium clocks. The key factors for achieving high performance of optically pumped compact cesium clocks are the cesium beam tube, laser frequency stabilization, and circuits. The frequency stability of the optimized optically pumped compact cesium clock exceeds by more than twice that of the 5071A high?performance cesium beam tubes, with a typical value of 3 × 10^-12 / τ^1/2. Eight optically pumped compact cesium clocks have been developed in the past three years. And the commercial high performance optically pumped compact cesium clocks have been preliminarily realized