We report on a β- barium borate(BBO)optical parametric oscillator injectionseeded with a narrow bandwidth pulsed Ti:sapphire laser.This device is pumped by onlyone Nd: YAG laser.The pump source of the Ti:sapphire laser is the residual secondharmonic(532 nm) in frequeney-tripling(355 nm,OPO's pump source)of the Nd: YAGlaser.As the Ti:sapphire laser does not consume other energy,thus the overall energyconversion efficiency is high.The signal coversion efficiency is up to 25%, and a narrow bandwidth (<0.01 nm) continuous tunning range of 589～892 nm is achieved.