The parameters for a cousto-optic mode-locking of an Ar+-laser investigated. The stable mode-locked operations at 488.0 nm and 514.5 nm have been obtained. The average power is up to 300 mW. The pulse-width is about 200 ps. The fluctuation of the pulse amplitudes is less than 5%. A dye laser with an astigmatically compensated cavity synchronously pumped by this Ar+-laser has been operated. Its pulse-width is less than 10 ps, and the average power is about 20 mW at 584.0 nm. The pulses of mode-locked dye laser are wavelength tunable over the range 570.0~620.0 nm, Particularity，the effects of the mismatch of the cavity length oi frequency on the made-locking behaviour axe emphasized.