The key factor for the success of the qualitative change in the accumulation of farmers’ livelihood capacity is to find the critical point of their livelihood capacity，that is，the accumulation of farmers’ livelihood capacity needs to reach a certain amount to stimulate farmers to get rid of the constraints of sustained poverty，which corresponds to the matching results of "high-energy/low-poverty" and "low-energy/high-poverty".Using micro-data of poverty-stricken areas in Shaanxi Province，this paper investigates the impact of livelihood capacity on the threshold of sustained poverty of farmers.The results show that under different thresholds，there is a significant non-linear relationship between the total index and each dimension of livelihood capacity and farmers’ persistent poverty，that is，there is an obvious "threshold effect".The result of the threshold regression test demonstrates that the threshold values of social capital，financial capital，human capital，material capital and natural capital and poverty sustainability of farmers are 0.696，0.763，0.808，0.611 and 0.235 respectively and the threshold values of livelihood capacity and poverty sustainability of farmers are 0.622.When the accumulation of farmers’ livelihood ability exceeds a certain threshold value，the livelihood ability will significantly reduce the duration of farmers’ persistent poverty，and the negative impact of livelihood ability on farmers’ persistent poverty will gradually increase.In addition，the interaction of social capital，financial capital，human capital and material capital can significantly reduce the duration of farmers’ persistent poverty.