Delay is the foundation for accurately measuring network performance metrics such as delay jitter, bandwidth, etc. While the delay measurement methods currently used have poor precision, for there exist clock errors and location errors. In this paper, an improved method for delay measurement is proposed. It replaces system clock with TSC (time stamp counter) register as time-stamping to eliminate clock errors, and it removes the time-stamping place from application to network driver to eliminate location errors. The precision has been elevated largely. Experiments show that when comparing with traditional methods under different packet lengths, the improved method can reduce measurement errors 21%~150%, and the measured delays are more stable. Furthermore, it basically has no effect on system throughput. The improved measurement method is based on general PC, so it has lower measurement cost and can be applied widely.