Cracks often occur to underwater joints of jacket platforms under internal and external loads. In order to prevent further damage or failure of joint points, the grouting clamp repair method is proposed and carried out for underwater complex tubular joints. Based on the complex tubular joint crack repair problem of a platform in Bohai, the clamp general design concept , slices structure design and grouting appurtenant structure design are discussed.Design reasonability and reliability are verified by finite analysis and testing. The grouting clamps to repair the under water tubular jacket joints is applied successfully in civil offshore engineering for the first time,achieving good repair result,which can provide technical references for the grouting clamp repair technology.