Studies heart rate testers based on integration heartbeat detection chip and introduces other components of the testers such as reflective infrared sensor, single-chip and LED display. The study is mainly based on the principle which the semi-transparency of human tissue changes as the heart throbs. (that is, when the blood flows into the human tissue, the semi-transparency reduces, when the blood flows back to the heart, the semi-transparency increases). Detects the change by infrared sensors and amplifies the signal through ASIC, thus obtains heartbeat frequency.