Optical properties of a new type metal coordination complex nonlinear optical crystal zinc cadmium thiocyanate (ZCTC) are reported. Refractive index is measured and phase-matching angles are calculated. Direct frequency doubling of diode laser radiation has been achieved using ZCTC crystal at room temperature. With 473 mW input power of 808 nm GaAlAs diode laser, 390 μW output at 404 nm violet light were produced. Experimental results show that ZCTC crystal is a promising excellent violet nonlinear optical material for frequency doubling of diode laser.