In recent years, IC design technology has developed rapidly, and the use of third-party intellectual property (3PIP) soft cores has become mainstream. In which maliciously implanted hardware Trojans maliciously tamper with the original circuits have become a core security threat to ICs. Based on the grey scale map analysis IP soft core hardware Trojan detection method is to use the RTL level program written in the IP soft core mapped into a grey scale map and then start matching detection. This paper briefly describes the basic concept and classification of hardware Trojans, the results of current research, gives the results of greyscale mapping analysis and detection, and experimental verification of B19-T100 hardware Trojans, which account for only 0.11% of the Trojan-free circuits. Through the analysis of the results found that when the matching block resolution of 500, the hardware Trojan recognition rate of 100%, continue to increase the resolution of the detection effect has no effect; when the matching block resolution is reduced to 300, the hardware Trojan recognition rate of only 5.38%, continue to reduce will make the recognition rate even lower. Under the premise of guaranteeing the detection effect, reducing the resolution of matching block can increase the number of detection samples, improve the detection rate, enhance the detection effect, and achieve the detection of hardware Trojan.