Eight prestressed steel reinforced concrete beam (PSRCB) and six steel reinforced concrete beam (SRCB) have been done with different compressive strength of concrete, rebar ratio, cover thickness, steel cover thickness and degree of prestressing. A compared study on the mechanical properties between PSRCB and SRCB were carried out, which included flexural capacity, deflection and maximum crack width. Experimental study indicates that PSRCB has better mechanical performance, higher flexural capacity, larger stiffness and better resistance to crack.