The multipath is a serious of error source in both the static and the kinematic GPS measurements. The positioning accuracy is being degraded due to multipath signal. The multipath detection depends on the difference of carrier to noise (C/NO) between the reference station and the rovers. It is focused on signal strength fading due to reflection and masking by surrounding objects such as trees and buildings. This paper shows the method to detect multipath and the example to improve the positioning accuracy by using the L1 signal processing in the different multipath environments.