Abstract: This paper aims at the problem that the fall irrigation quota of drip irrigation farmland under mulch cannot be effectively determined due to the extremely uneven spatial distribution of water and salt and the significant effects of freezing and thawing in the seasonal freeze-thaw area. In response to this problem,based on the field experiment data,this paper uses the joint simulation method of HYDRUS-2D and SHAW model to simulate the soil water and salt dynamics under different autumn irrigation quotas under the conditions of the Yellow River water irrigation,and studies the single and multi-year autumn irrigation quota of drip irrigation farmland under mulch. The results show that:（1） When the single year autumn irrigation is conducted,for mildly saline soil,the recommended autumn irrigation quota is 1 100m3/hm2;for moderately saline soil,the recommended autumn irrigation quota is 2 100 m3/hm2;for heavily saline soil,the recommended autumn irrigation quota is 2 500 m3/hm2when only for the purpose of improving soil quality.（2） When irrigating in autumn every few years,the non-saline soil should be irrigated in autumn at least once every 3 years. The recommended autumn irrigation quota is 2 000 m3/hm2for irrigation every three years,and the recommended autumn irrigation quota is 1 350 m3/hm2for irrigation every two years.The soil with mild,moderate and severe salinization must be irrigated in autumn every year.