The invention provides a two-stage connectionless protocol resource allocation method with collision detection, in particular comprising the following steps: S1, determining a scheduling request derivative ns, SR (i) and a number of time-frequency resource blocks Rdata (i) allocated to data transmission based on the collision detection function; S2: acquiring the number of time-frequency resourceblocks RSR (i) and RSR (i-1) allocated to the scheduling request in the current access cycle and the previous access cycle; S3: determining the number of time-frequency resource blocks allocated to the scheduling request in the next access cycle according to formula shown in the description, wherein delta (i) = ns, SR (i)-Rdata (i) denotes the difference between the leading derivative of the scheduling request successfully transmitted in the current access period and the number of time-frequency resource blocks allocated to the data transmission, delta (i-1 ) denotes the difference of the previous access period, and i denotes the sequence number of the access period. The effect is that the complexity of the two-phase connectionless access protocol which needs to feedback the three-state information of the scheduling request is traded, and the optimal resource allocation without the estimation of the number of users is realized by using less performance loss.