Kelp liquefaction rate as technical index, by biological enzymolysis technology, the enzymatic hydrolysis conditions were optimized, such as granularity, substrate concentration, reaction temperature, reaction time and pH, and the monosaccharide composition and oligosaccharide polymerization degree of kelp enzymatic hydrolysate were also analyzed separately by the high performance liquid chromatography (HPLC) and high performance gel permeation chromatography (HPGPC). The result suggested that the optimum conditions of rapid liquefaction of kelp were as followed: the size of raw material 100 mesh, the ratio of material to liquid 1︰12 (g/mL), pH 8, reaction temperature 50, and reaction time 12 h. Under this condition, the liquefaction rate of kelp could reach to 71%. Analysis results of monosaccharide composition and oligosaccharide polymerization degree of kelp enzyme solution: the contents of non saccharide impurities, oligosaccharides and monosaccharides were 54.8%, 18.9%, 27.2%, respectively, in the dry matter of kelp enzymolysis liquid; the content of oligosaccharide above 6 sugar were larger than 3～6 suger; the content of uronic acid was the highest in monosaccharide. In this paper, the kelp enzyme solution has the advantages of simple process, convenient operation, high enzymolysis efficiency, and small molecular substances degraded from large molecules are more conducive absorption to animal and plant. The method expand the application field of kelp enzyme solution.