Drought is the primary abiotic factor that affects the yield and quality of cotton fiber. ROP （Rho-realted GTPases from plants）protein is a type of plant-specific Rho small G proteins，and in plants this protein plays a role in responses to the development and various stresses. In this study，real-time quantitative polymerase chain reaction（qRT-PCR）was used to analyze the expression pattern of the GhROP4 gene under drought stress and exogenous abscisic acid（ABA）treatment conditions. Virus-induced gene silencing（VIGS） technology was used to analyze the regulation mode of the GhROP4 gene on drought and the possible regulatory pathways involved. Drought and abscisic acid treatment increased the transcription level of GhROP4 gene as a whole，and silencing GhROP4 gene enhanced the drought resistance of cotton. The water loss rate and relative water content，proline（Pro，Proline）content，and activities of three antioxidant enzymes：catalase（CAT）， superoxide dismutase（SOD），and peroxidase（POD）of the detached leaves of the silent plants after drought stress were significantly higher than those of the negative control. The contents of hydrogen peroxide（H2O2）and malondialdehyde（MDA）were significantly lower than those of the negative control；compared with the negative control，ABA synthesis and pathway gene expression in the leaves of silent plants were significantly up-regulated. Altogether，our results supported that the GhROP4 gene was a negative regulator in drought resistance of cotton through negatively regulating the ABA metabolic pathway