A fast anti-collision algorithm has been proposed to improve the identification performance of the EPC C1 Gen2 standard. The algorithm estimates the tag quantity and adjusts the frame size at a check point of a frame for each identification round. The Monte Carlo simulation is carried out to verify the performance of the proposed algorithm by using MATLAB. Simulation results show that the system throughput of our method can reach a value of up to 34%, which is very close to the theoretical maximum of 36.1% for the EPC C1 Gen2 anti-collision scheme. As compared to existing methods, the algorithm significantly reduce the complexity and improve the performance.