The invention provides a forced feeding, threshing, separating and smashing integrated device for first-harvest rice. The forced feeding, threshing, separating and smashing integrated device for first-harvest rice comprises a closed multifunctional threshing cylinder, a flow guide separable grass breaking top cover and a combined concave plate, wherein the threshing cylinder comprises a cylinder shaft feeding head and a cylinder body, a spiral blade is mounted on the feeding head, and an arc tooth group, a spike tooth group and a roller rotating blade group are distributed on the circumferenceof the cylinder body sequentially; the combined concave plate is located below the closed multifunctional threshing cylinder and comprises a transition concave plate, a threshing concave plate, a separating concave plate and a grass guiding concave plate sequentially; the flow guide separable grass breaking top cover is mounted above the closed multifunctional threshing cylinder and comprises a top cover inner shell and reinforcing plates, and the top cover inner shell comprises an adjusting mechanism, flow guide bars, punching plates and top cover fixed blades. The forced feeding, threshing,separating and smashing integrated device is applicable to feeding, threshing, separating and smashing of the first-harvest rice with different characteristics, has the advantages of compact structure, large separation area, light weight and the like, can effectively improve threshing performance and efficiency of the first-harvest rice and has lower power consumption.