In order to overcome the shortcomings of farms, such as high fecal water yield, small and scattered supporting arable land area, lack of small fecal water injection fertilization machine, low utilization rate of fecal water, a kind of equipment of self-propelled fecal water injection fertilizer applicator was developed. The capacity of the machine was 6m3, mainly composed of chassis, fertilizer tank, suction and discharge system and trenching fertilization syringe and other components. The complete machine structure and operational principle of the equipment were introduced. The research focused on the key components of the fertilizer applicator, such as tank structure, suction and discharge pipe system, control and monitoring system, fecal water divider and power extractor, which were designed and calculated. When the machine worked, it can realize the functions of fecal water multi-channel and multi-directional automatic suction and discharge, constant speed cruise, liquid circulating flow in the tank, furrow fertilization, injection cut-off and anti-blocking monitoring and alarm. According to the design requirements, the fertilizer applicator was trial produced, and the field experiment was carried out with pig farm manure as raw material. Experiment and test results showed that when the speed of the fertilizer applicator was 4km/h, the injection depth was 92.8mm, the stability coefficient of injection depth was 946%, and the consistency variation coefficient of fertilizer application was 5.3%. All indexes were consistent with the design value and met the agronomic requirements. The research result provided reference for the research and development of small self-propelled fecal water injection fertilization equipment.