A complete set of phase contrast kit can be flexibly equipped with an ordinary biological microscope to be a phase contrast microscope system for observing live cells. The compound Siedentopf trinocular microscope comes with trinocular viewing head, body frame, quintuple reversed nosepiece, four DIN achromatic objectives, large double layer mechanical stage, variable intensity halogen transmitted illumination system and a set of phase contrast kit. It offers eight levels of brightfield magnification 40X-1600X. The phase contrast kit includes a substage phase contrast condenser, a centering telescopic eyepiece, two plan phase contrast objectives with phase plate: 10X, 40X. It also offers four levels of magnification power: 100X-160X-400X-640X. This phase contrast microscopy is perfect for clinical, university or institutional uses.