To address the issue of soil pests and diseases in facility horticulture caused by continuous cropping obstacles and other factors, a soil steam sterilizer powered by a pulse combustor as a heat source was developed in this study. Based on the minimum steam requirement of 100 kg/h for the soil steam sterilizer, the minimum power of the pulse combustor was determined to be 28.2 kW. The pulse combustor mainly consists of a combustion chamber and a nozzle and used straight nozzles of 200, 400, 800, 1 000 mm, as well as an 800 mm bent nozzle. They could be combined via flanges into different lengths of straight nozzles(600, 800, 1 000, 1 400, 1 600, 1 800, 2 200, 2 600, 2 800, 3 000 mm) and bent nozzles (800 and 1 600 mm). The impact of different nozzle structures on the startup performance and operational stability of the pulse combustor was studied. The results showed that nozzles ranging from 800 to 2 600 mm could be activated. Working frequency and pressure amplitude had a linear relationship and higher frequency correlates with higher pressure amplitude. For straight nozzles of the same length, the fuel consumption rate, frequency and pressure amplitude were higher than those of bent nozzles. Under throttle conditions 2, 3, 4, the standard deviation of the pressure amplitude for the bent nozzle combustor was smaller, suggesting its better stability. The straight nozzle pulse combustor with a nozzle length of around 1 800 mm had the best performance. Therefore, selecting the bent nozzle pulse combustor with a nozzle length of 1 800 mm as the heat source for the steam generation unit of the soil steam sterilizer could ensure the operational characteristics of the pulse combustor while also promoting miniaturization of the steam generation unit.