The invention provides a portable high-sensitivity heavy metal detecting device based on a micro-fluidic chip. The device comprises a sample feeding unit, the micro-fluidic chip, a recycling unit, an absorption spectrum detecting unit and a control and data processing display unit. The sample feeding unit comprises a reagent storage device, a blank solution storage device, a sample storage device, a micro solenoid valve, a first micro electromagnetic pump and a second micro electromagnetic pump. The micro-fluidic chip comprises a first sample inlet, a second sample inlet, a detecting channel and a sample outlet. The recycling unit comprises a waste solution storage device. The absorption spectrum detecting unit comprises a light source, an optical resonator and a micro spectrograph. The control and data processing display unit comprises a control circuit and terminal equipment. According to the device, fast, real-time and in situ measurement can be achieved on heavy metal, and detecting sensitivity is high. The device is high in integration degree, small in size, light and convenient to carry and operate.