The invention aims to provide a liquid absorption fiber. The fiber comprises a polymer represented by the following structural form shown in the description, wherein R is at least one selected from a group consisting of -NH2, -OCH2CH2OH, -OCH2CH2CH2OH, -OH, -ONa, -OK and -OCa; m, n and p respectively represent the quantity percentages of corresponding repeating units in a polymer molecule, and meet the following relational expression: m+n+p=1, p/(m+n+p)=0.05 to 0.30; when the degree of substitution D is defined to be m/(m+n+p): the total degree of substitution of the fiber Ds is 0.09 to 0.8, and the value of the degree of substitution Do of the polymer at the center point of the cross section of the fiber/the degree of substitution Dx of the polymer on the edge of the cross section of the fiber is 0 to 0.98. By the use of a simple process, the antibacterial performance, the liquid absorption property and the like of the fiber are improved by controlling the proportions of the repeating units with different substituent groups in the polymer contained in the fiber and enabling the degree of substitution of the outer side (edge) of the fiber to be greater than that of the inside (center) of the fiber; the fiber suitable for clinical application, particularly applicable in the aspects such as hemostasis, burns and chronic wound treatment, is provided.