A method, a device, and a system for resource allocation are provided to improve network capacities. The method implemented by an access network device includes: obtaining a first quantity of repetitions M and a first MCS order that are of a scheduling resource of a first terminal, and a second quantity of repetitions N and a second MCS order that are of a scheduling resource of a second terminal; calculating overlapping areas of first and second total scheduling resources based on the first and second quantities of repetitions and the first and second MCS orders, respectively; determining a maximum overlapping area of the first total scheduling resource based on the calculated overlapping areas; and allocating to the second terminal, N consecutive scheduling resources overlapping with the first total scheduling resource, wherein an overlapping area is less than or equal to the maximum overlapping area.