The invention discloses a reinforcement method of a concrete beam span. The reinforcement method is characterized by comprising the steps that two pushing stopping anchor plates are fixedly installedon a to-be-reinforced beam, two prestressed steel plates with long holes in the middles are arranged between the two pushing stopping anchor plates, a pushing connecting port is reserved between the two prestressed steel plates, and a pushing mechanism is arranged at the pushing connecting port; anti-expansion studs are arranged on the to-be-reinforced beam, at the corresponding positions, of thelong holes; structural adhesives are applied to the prestressed steel plates, the long holes of the prestressed steel plates penetrate through the anti-expansion studs on the to-be-reinforced beam, and the pushing starting edge abuts againstthe pushing stopping edge for fit installation, and nuts are additionally arranged on the anti-expansion studs and tightly twisted; and before the structural adhesives are fully solidified, when prestress is applied to the prestressed steel plates through the pushing mechanism and a set value is reached, the pushing connecting port is welded as a whole, thenuts on the anti-expansion studs are tightly twisted, and the pushing mechanism is removed after the structural adhesives are fully solidified. According to the reinforcement method of the concrete beam span, reinforcement and strengthening can be conducted under the condition that the concrete strength of the beam is insufficient, and the reinforcement method has the advantages of small amount of construction, convenient construction and low cost.