Trichoderma spp. is an important biocontrol microorganism in the fungal disease prevention and control of green agriculture. Which is widely developed as Trichoderma agent for biological control, biofertilizer and soil amendment. The development of traditional Trichoderma fungicide is limited to the screening of Trichoderma strains and the optimization of fermentation conditions. Therefore, it is necessary to explore a new application mode of Trichoderma. Due to intolerance to storage and high costs of transportation and development, coconut water is often directly discarded as waste in the production of coconut industry. In this study, coconut water was compounded with Trichoderma spores and medium elements as water-soluble fertilizers to explore the effects on seed germination and seedling physiological indexes of cucumber. The results showed that adding medium element to coconut water and adjusting pH to 7 had the best effect on the production of Trichoderma spore, and the sporulation reached 2.32×10⁷ CFU/mL. The treatment group A of water-soluble fertilizer compounded with medium element in Trichoderma spp. and coconut water and treatment group B of water-soluble fertilizer compounded with Trichoderma spp. and coconut water significantly promoted the germination of cucumber seeds, and the germination rates of cucumber seeds was 94.44%and 87.50%, respectively, compared with sterile water (CK), which increased by 28.30% and 18.87%, respectively. Pot experiment showed that the plant height and root length of treatment group A was 24.01 cm and 27.76 cm, respectively, which was 48.03% and 47.27% higher than those of CK, which significantly promoted the growth of cucumber seedlings. At the same time, the fresh weight and dry weight of stem and root of cucumber seedlings in treatment group A were also significantly higher than those of CK. Further, we determined the content of total chlorophyll, reducing sugar and soluble protein, the activity of peroxidase (POD) and catalase (CAT) of cucumber seedlings in treatment group A, compared with CK, which increased by 97.46%, 66.32%, 58.85%, 32.67%, and 40.31%, respectively; and the content of malondialdehyde (MDA) was significantly decreased, which was 79.96% lower than that of CK. In summary, the treatment group of water-soluble fertilizer compounded with medium element in Trichoderma spp. and coconut water could significantly promote cucumber seed germination and seedling growth, improve the contents of total chlorophyll, reducing sugar, soluble protein, POD and CAT activity, decrease MDA content of seedlings, and enhance the ability of cucumber to resist stress.