Abstract: It is very important to select clay anti-swelling agents according to the reservoir characteristics in offshore oil field, and significant to control reservoir damage and protect water-sensitive reservoir to guarantee sustainable and efficient development of the entire field. Through comprehensive evaluation with static and dynamic experimental evaluation, with various evaluation methods on anti-swelling agent, clay anti-swelling agents for water injection in offshore oil field have been selected. For the optimized FP-3A clay anti-swelling agent with mass fraction of 1%, centrifugal expansion rate is 79.1% with static evaluation method, and 54.6% by X-ray diffraction method, 80.7% by dilatometer method, and core linear expansion rate is 0.73%. The static adsorption amount is 0.29 g per 100 g. The permeability retention rate is greater than 70% with dynamic evaluation method, and the best injection concentration is 0.5%to 1.0%. In addition, the range of permeability change is small, and the anti-swelling effect is stable for a long period of time. Therefore, FP-3A clay anti-swelling agent is suitable for the development of offshore oil field.