Abstract: To optimize solid-state fermentation conditions for biocontrol agent Trichoderma harzianum FJAT-9040, the agricultural by-product pig-raising beddings fermented by microbes were used as the main medium components and the polypropylene plastic bagged cultivation method was used to perform the solid-state fermentation of the FJAT-9040 strain. The effects of inoculation method, medium volume and culturing time on growth of the FJAT-9040 strain were analyzed comprehensively. Subsequently, the effects of the fermentation products on bitter gourd growth and their biocontrol efficiency against bitter gourd Fusarium wilt in field plot experiments were detected, respectively. Our results demonstrated that the treatment groups of inoculation before compost bagging were superior to those of inoculation after compost bagging in the aspect of inoculation method. The results of comprehensive comparison showed that colonies yield of the FJAT-9040 strain reached its maximum on the 18th to 20th day when the medium volume was 60%-70% and the inoculation method was inoculation before compost bagging. The highest colonies yield of the fermentation products could be (4.33- 4.46)×10⁸ spores/g, which was increased four orders of magnitude in relative to the initial inoculum dosage. At this time, the hyphae of FJAT-9040 were bottle green according to the observation of the appearance and broadly distributed the whole culture bag. Importantly, the treatment of bitter gourd seedlings with 5% or 10% T. harzianum FJAT-9040 biological fertilizers could significantly promote the growth of root length with increase of (8.0-8.3) mm and vine length with increase of (27.5-51.2) mm, whereas the treatment had no significant influence on leaf number. After the twice treatments with T. harzianum FJAT-9040 biological fertilizers, the control efficiency against bitter gourd Fusarium wilt could be 61.21%, which was very similar to the control efficiency (59.93%) of treatment with the chemical agent carbendazol using the same treatment methods.