Nanchong is a famous cultural city with a long history of 2200 years. It is the central city in northeast Sichuan and the second largest city in Sichuan Province. It is located in the middle reaches of Jialing River in the northeast of Sichuan Basin. It is a bright pearl along the ancient Jialing River, a famous hometown of silk and a prestigious fruit state, with an area of 12494 square kilometers. By the end of 2008, the total registered population was 7,494,900, and the urban population reached 8,494. Geographical coordinates are 30 35' ~ 3151'north latitude, 0/05 27' ~106 58' east longitude, north-south span 165 km, and east-west span/kloc-. Nanchong City is located in a typical humid monsoon climate zone in the middle subtropical zone, which has the common climate characteristics at the bottom of Sichuan Basin: four distinct seasons, warm winter, early spring, hot summer, autumn rain and cloudy. However, compared with the Yangtze River basin south of the basin bottom, there are differences in low temperature and heavy rain. Compared with the western Sichuan plain, the ratio of high temperature to spring rain is significantly different.

The monsoon in Nanchong city changes obviously in winter and summer, and the air flow in winter comes from the northern high latitude area, with low temperature and less precipitation. However, compared with the middle and lower reaches of the Yangtze River at the same latitude, Nanchong is warmer because it is located in the abdomen of the basin and the Qinba Mountain area in the north blocks the cold air from going south. In summer, the south wind blows more, the climate is hot and the precipitation is concentrated. There is little difference in the average temperature in different parts of this city. Annual average temperature 15.8℃- 17.8℃, monthly average temperature 5℃-6.9℃, and July average temperature 26℃-28℃. Except in mountainous areas, frost and snow are scarce, the frost-free period is as long as 290-320 days, and the active accumulated temperature ≥ 10℃ is 4800℃-5700℃. Crops can be harvested twice a year, and wintering crops can be safely wintered. Due to the high terrain and low temperature, the vertical difference between the low mountainous areas in the north is obvious.

The annual precipitation of the whole city is between 980- 1 150 mm, decreasing from southwest to northeast. The seasonal distribution of precipitation is uneven, accounting for about 45% of the whole year in summer, 25% in autumn, 5% in winter and 25% in spring, with great variability. After entering the midsummer, due to the continuous high temperature, sunny and hot weather, Nanchong often suffers from drought, which has a great impact on crop growth. Especially the south-central part is one of the areas with severe drought in midsummer in Sichuan Basin. In autumn, affected by the topography of the basin, it rains continuously, with heavy clouds and less sunshine. In addition, it is foggy in winter, and the average sunshine for many years is only 136.73 hours, which is a region with less sunshine in the province, which limits the photosynthesis and nutrient accumulation of crops.