In order to study the effects of different biological pesticides samples on the droplet characteristics with different types and size hydraulic nozzles, a particle/droplet laser image analysis system and a portable spray pattern analyzing system were used to investigate the spray droplet characteristics of biological pesticides with hydraulic nozzles. Spray parameters included the spray droplet size distributions and spray pattern widths. Seven different spray samples (water and six types of biological pesticides manufactured by Bioworks Inc.) were tested with two Teejet flat fan nozzles (XR8004 and XR11004) and two Teejet hollow cone nozzles (TXA8002 and TXVK8004) under laboratory conditions. Droplet size distribution was evaluated at the same and different spray pressures separately and the same spray height. In addition, the spray pattern width was determined at the same spray pressure and the same spray height. The results showed that there was no significant difference between the droplet size of the liquid biological pesticide after mixing with water in a certain proportion and the droplet size of water, and the droplet size of the liquid biological pesticides was higher than that of the powdery biological pesticide mixture with water. The droplet size of biological pesticide sprayed was decreased as the spray pressure increase for the same nozzle;the droplet size distribution uniformity was decreased as the increase of the nozzle flow rate, and the larger the spray flow rate was, the more dispersed the particle size was. The spray pattern width was increased as the increase of the spray angle, and different biological pesticide samples had little effect on the spray pattern width. Therefore, proper selection of nozzle types, spray pressure and flow rate was necessary for discharging particular biological products to achieve optional spray application efficiency and effectiveness.