We propose and experimentally demonstrate an on-chip switchable polarization beam splitter (PBS) using silicon waveguides. To the best of our knowledge, it is the first demonstration of an on-chip PBS that is not only able to split polarization beams but can be tuned to allow these beams to switch the output paths. The design of the switchable PBS is based on a directional coupler. Measurements show extinction ratios of >12 dB in both the initial state and the switched state, which is realized by heating the device up to 57°C. By adding switching ability to an on-chip PBS, this work is expected to benefit quantum technology, communications, microwave photonics, etc.