Abstract: In order to solve the insufficient information of the guide signs at the grassland highway intersection, an indoor simulation test scenario was built to analyze the information of 30 drivers’ β, α/β brainwave and Mismatchnegativity（MMN） and P300 brain topographic maps changes, determining the threshold value of the amount of information of the intersection guide signs, and verifying the research results through the correct response rate and response time. The results showed that, according to the changes of β and α/β, the appropriate information signs of the intersection guide was 6 or 7; according to the analysis of MMN and P300 brain topographic maps of drivers, the appropriate information signs of the intersection guide was 5 or 6. Through the drivers’ correct response rate and reaction time, it was further verified that the number of intersection guide signs was 5 or 6. Therefore, suggesting that the information threshold of the guide signs at the grassland highway intersection is 5 or 6, which can ensure that the driver can accurately identify the effective information, ensuring the traffic efficiency and driving safety.