The invention provides a portable nucleic acid isothermal amplification instrument. Directed at the detection characteristics of animal epidemic diseases and based on an open source Arduino hardware system, the instrument adopts a programmable isothermal amplification technology, and comprehensively covers isothermal detection methods. While realizing the detection function, hardware and software can be upgraded according to needs, existing isothermal amplification technologies can be corrected and new detection methods can be developed. The isothermal amplification instrument provided by the invention takes a universal controller Arduino uno as the main control panel, employs an independently developed full-bridge control panel to control a Peltier device in terms of heating and cooling circulation on an aluminum block, thus realizing a constant temperature. According to the control process, after thermistor and 22-bit high precision A/D conversion, then the conversion result is sent to Arduino for processing, and on-off of a bridge arm can be controlled in real time by pulse according to the processing result. At the same time, a graphic software platform is researched and developed independently, and the temperature and reaction time can be controlled independently.