Through collecting and collating information of 62 tunnels with initial support fracture，the risk grade is summed up，the factors causing initial support fracture are divided into two types：objective factors and subjective factors. The statistical results show that the proportion of controlled subjective factors’ reached as large as 25%. The comprehensive evaluation model on safety of mountain tunnel initial support by analytic hierarchy process (AHP)and fuzzy comprehensive evaluation is established. On this basis，the science rational risk response method is required. Then the evaluation model is proved credible by field measurements.