In the Optical interconnect system of data center, a digital signal processing scheme for joint equaliza- tion and timing recovery feedback loops is proposed to address the issue of conflicting prerequisites between the clock recovery module and equalization module due to their interdependence. This scheme adopts an improved Gardner feed- back all digital clock synchronization algorithm based on the characteristics of PAM4 signals to reduce clock recovery errors and improve convergence performance; In the equalization module, an improved cascaded multimodal blind e- qualization algorithm based on T / 2 fractional interval was proposed and adopted to reduce steady-state error and im- prove signal equalization performance. The simulation results show that this joint scheme can reduce the system error rate. Under the condition of meeting the hard decision forward error correction threshold, the receiver sensitivity after 40 km transmission is -16dBm, which is improved by at least 3dBm compared to the cascaded scheme. Meanwhile, the joint approach has a stronger ability to resist sampling clock offset (SCO), with a maximum tolerable increase of approximately 200 clock offsets, indicating that this scheme can effectively compensate for linear damage and clock er- rors.