A method for cross-linking hyaluronic acid, or one of its salts, and optionally other biocompatible polymers, characterized in that it comprises at least the steps of: a) preparing a first aqueous phase of hyaluronic acid, and optionally other biocompatible polymers, partially cross-linked, characterized by: - the addition of hyaluronic acid or one of its salts and optionally other biocompatible polymers, in an aqueous solution in order to obtain a concentration of C1 hyaluronic acid - the addition of a quantity Q1 of crosslinking agent - to achieve crosslinking partial of the hyaluronic acid when controlling the temperature T1 and the duration t1 of the cross-linking reaction, wherein the first aqueous phase prepared of partially cross-linked hyaluronic acid is not converted into particles； b) preparing at least a second aqueous phase of hyaluronic acid, and optionally other biocompatible polymers, partially crosslinked, characterized by: - the addition of hyaluronic acid, or one of its salts and optionally other biocompatible polymers, in an aqueous solution with in order to obtain a concentration of C2 hyaluronic acid - the addition of a quantity Q2 of crosslinking agent - to achieve partial crosslinking of hyaluronic acid by controlling the temperature T2 and the duration t2 of the crosslinking reaction, wherein, at least a second aqueous phase prepared of partially crosslinked hyaluronic acid does not become particles； c) adding the at least one second phase of partially crosslinked hyaluronic acid in the first phase, and then producing a mixture of said at least two phases by optionally adding an additional amount Qm of crosslinking agent； and d) continue the cross-linking of the mixture prepared in advance by controlling the temperature Tm and the duration tm of the cross-linking reaction, wherein the cross-linking method does not involve the addition of cross-linked hyaluronic acid particles or one of their salts, or of any other polymer, during steps a, b,
