The invention relates to the technical field of medical apparatus and instruments, and particularly discloses a single-stage
venous cannula capable of adjusting infusion amount and a flow
rate control method of the single-stage
venous cannula. The adjusting mechanism comprises an adjusting seat, a screw rod and a driving
assembly, the outer side of the
insertion pipe is sleeved with the adjusting seat, the screw rod is in threaded connection with the interior of the adjusting seat, the end of the screw rod is used for abutting against the
insertion pipe, and the driving
assembly is used for driving the screw rod to rotate; the driving
assembly comprises a connecting column, an inserting rod and a first elastic piece, the connecting column is connected to the screw rod, the inserting rod is movably inserted into the adjusting seat, an inserting piece is arranged on the inserting rod, and an inserting hole for the inserting piece to be inserted in is formed in the connecting column. After the adjustment process is completed, the connection between the
insertion rod and the screw rod can be disconnected, so that the situation that the set flow speed is accidentally changed due to the fact that a patient touches by mistake, clothes rub or the transfer process can be effectively prevented, and infusion safety is guaranteed.