Contributions of red, green and blue components of color liquid crystal television to the transmittance of a He Ne laser beam should be clarified. Experiments show that there is an approximate linearity in quite a large range for the red and green components. The green component is even more active than the red, but the blue is inferior. It is possible to reduce the loss of spatial resolution by virtue of the spectrum coincidance of the filters and the non linearity of liquid crystal. It is also observed that the three color components have a strong dependence on each other. Only considering both lightness and interaction of the three components can bring about the best effect of color-liquid-crystal-television in a coherent beam.