Abstract: This article was aimed at physicochemical interaction between epoxy resin and carbon fiber under composite processing conditions. The influences of temperature on surface tension of E51 resin,  E51/DDS and E51/imidazole systems, contact angle between E51 resin and T700 fiber,  and the initial apparent contact angle between E51 resin and T700 fiber bundle were studied first; and then the contact angle between E51/DDS and T700 fiber was investigated,  based on what the thermodynamic work of adhesion was calculated. The results indicated that wetting between epoxy resin and fiber can be improved by increasing the temperature and lowering the viscosity of resin,  of which the effect of the latter is more significant. Before chemical reaction of the epoxy system started,  improvement of adhesion between fiber and resin was not significant by increasing the temperature.