We demonstrate a high energy picosecond optical parametric generation and amplification (OPA) system in the visible range based on two type-I phase matched β-barium borate crystals, in a walk-off compensating geometry. The second harmonic of a two-stage 60 ps Ti:sapphire laser amplifier at 10 Hz repetition rate serves as the pump. The signal is continuously tunable from 460 to 750 nm, which covers most of the visible range. The corresponding tuning range in the idler branch is from 0.86 to 3.07 μm. At a pumping energy of 110 mJ per pulse, the signal pulse energy is at 20 mJ class for most of the tuning wavelength in the OPA stage, and reaches a maximum of 33 mJ at 710 nm, corresponding to a conversion efficiency of ~ 30%.