Generally, lighting designs originated from designer’s experience, and the lack of understanding spectrum and landscape formation results in unexpected effect, like discrepancies of lighting and landscape, excessive lighting, light pollution, etc. Based on spectrum theory, relationship between illuminant color and object color had been discussed, and through taking an object color sample as a reference, lighting effect of traditional light sources, LED light source and a variety of monochromatic spectrum light sources had been studied. Effect of light sources’ spectrum on environment had been analyzedand, general rules of landscape lighting effect are achieved.The results make it possible to theoretically predict architectural lighting design effect in the design procedure and help to choose appropriate light spectrum. Based on spectrum theory, landscape lighting effects can be fully quantified.