Aiming at the problem of tag collision in batch tag recognition in food quality traceability, a RFID multi tag recognition anti-collision algorithm was proposed by combining frame slotted ALOHA algorithm and minimum mean square error precoding technology. Before multi label recognition, the algorithm uses precoding technology to group the tags, which can effectively reduce the collision between tags. The simulation results show that the improved algorithm can effectively improve the performance of RFID multi tag recognition, and has a certain practical value.