Abstract: To solve the problem of agricultural waste rape stalks and develop new wall materials, we treated the rape straws with alkaline and used the proportion of the sand rate and rape straws as the variable to make test pieces with size of 300 mm× 300 mm× 30 mm, then, we tested their thermal conductivity by a steady-state flatpanel thermal conductivity meter from the macroscopic perspective, and scanned the microstructure inside the concrete by a SEM, in order to study the thermal insulation performance of the rape straw fiber reinforced concrete from the microscopic perspective. The results showed that for each test group and control group with different straw contents, the thermal conductivity of concrete with 25% sand ratio was 10% lower than that with 40% sand ratio, generally speaking, the higher the sand rate, the higher the heat conductivity, and the larger the coefficient, the worse the insulation performance. For test group and control group with different sand rates, the thermal conductivity coefficient of concrete specimens with 2.5% straw content was about 30% lower than that with 0% straw content, that is, the greater the straw amount, the smaller the thermal conductivity, and the better the insulation performance.