We present a continuously tunable Alexandrite laser. By means of chromatic dispersion prisms, the output spectrum in the range of 725-781 nm has been obtained. The output energy at the center wavelength of 750 nm has achieved 1 J per pulse. To obtain the highest output energy, the best transmission rate of output mirror has been briefly studied. By reducing the transmission rate of the output mirror, the output range of spectrum has been extended to 725-791.4 nm. The difference between tuning with one and two prisms has also been analyzed experimentally.