A simulation method for flow field of multi-stage fracturing on horizontal well in tight oil reservoir is provided. The tight oil reservoir comprises multiple horizontal wells with multi-stage fracturing, and for any horizontal well of the multiple horizontal wells, the method comprises: establishing a seepage mathematical model involving threshold pressure gradient according to reservoir physical property data and production data of the horizontal well, and determining formation pressure distribution of the horizontal well after multi-stage fracturing production according to the seepage mathematical model; determining formation pressure field distribution of the horizontal well after multi-stage fracturing production according to the formation pressure distribution and basing on principle of complex potential superposition; and establishing a criterion for identifying effective producing range of the horizontal well according to the formation pressure field distribution, and determining flow field range of the horizontal well according to the criterion.