The resource utilization of protein in excess sludge is a research hotspot at home and abroad, and sludge pretreatment is an important way to realize protein release from sludge. In order to further improve the dissolution efficiency of protein in excess sludge, this paper selected thermal-alkali pretreatment, ultrasonic-alkali pretreatment and lysozyme pretreatment as the method of disintegration in sludge, and optimized the parameters with the protein extraction concentration as the main index. The isoelectric point method was also used to purify and recover crude protein. The results showed that the cellulolytic effect:thermal-alkali pretreatment (pH 13, temperature 140℃, time 1.5 h, 2 062.98 mg/L) > ultrasonic-alkali pretreatment (497.76 mg/L) > lysozyme pretreatment (269.95 mg/L), and the protein purification recovery of thermal-alkali pretreatment at pH 3 can reach 62.42%. It can be seen from the above test results that the thermal-alkali pretreatment has obvious advantages over the other two methods in terms of extraction effect, deserving of exploitation and utilization.