The main objective of this study was to evaluate the capacity in phosphorous solubilization under a number of different environmental conditions and antagonism against the Fusarium solani fungal strain of the fungus Aspergillus niger H4.7 (H4.7), a well organic material decomposer, isolated from the agricultural soil in Soc Trang province under the laboratory condition. The experiments for testing a number of different environmental conditions including pH, NaCl salt concentration and the solubilizing ability toward two insoluble phosphate forms (FePO4 and AlPO4) were carried out in NBRIP liquid culture medium while the antagonistic activity test of the strain H4.7 against the plant pathogenic fungus, Fusarium solani was conducted on PDA medium. The results showed that the fungal strain H4.7 gave the best result in phosphate solubilization and in biomass formation under the condition of cultural medium like pH=7 and 0% NaCl. Moreover, Ca3(PO4)2 was solubilized the most followed by AlPO4 and FePO4. Besides, results also revealed that the fungal strain H4.7 also had a good function in resisting the plant pathogenic fungus, Fusarium solani causing plant root rot diseases, especially, at 5 days of incubation, the antagonistic performance of the fungal strain H4.7 was achieved at 49.2%