The invention provides a multi-user scheduling method and system of a full-duplex cache relay system. The multi-user scheduling method comprises the following steps that: a relay node acquires the number N of user pairs according to registration resource request information of users, dividing a cache region, and forming N cache queues corresponding to the N pairs of users, wherein the capacities of the cache queues are limited, and the length Bi is 0 at the very beginning; the relay node broadcasts a pilot signal to all the users, estimates channel parameters and acquires a channel fading distribution situation; and the relay node acquires sending power of each pair of users or an upper limit of a sending power average value and additive Gaussian white noise variances sigma1i and sigma2i,calculates a selection coefficient, and schedules the users according to the calculated selection coefficient. The multi-user scheduling method provided by the invention solves the problem on cache queue scheduling under a multi-user environment in a full-duplex cache relay communication system, effectively uses a multi-user diversity gain of the system, can fully make use of the cache action, andgreatly increases the throughput capacity of the system.