The invention relates to an unsaturated carboxylic acid in-situ polymerization-crosslinking formaldehyde-free non-iron finishing method of cellulose fiber fabric. The method comprises the following steps: (1) preparing a formaldehyde-free non-iron finishing solution at a room temperature: mixing unsaturated carboxylic acid, a catalyst, a radical initiator, a softening agent, an osmotic agent, and water, and stirring to dissolve the components so as to obtain a uniform and stable non-iron finishing solution; (2) soaking fabric into the formaldehyde-free non-iron finishing solution until the liquid content is in a range of 60 to 90%, baking the fabric at a temperature of 70 to 100 DEG C for 1 to 5 minutes, and then baking the fabric at a temperature of 160 to 190 DEG C for 30 seconds to 8 minutes. The solution preparation and fabric soaking can be carried out at a room temperature, the temperature of the finishing solution does not need to be maintained in a certain range, moreover, the drying time is very short, and formaldehyde is not used during the processing process or after the processing. The wrinkle recovery angle of the processed fabric is larger than 270 degrees, the DP grade is not less than 3.3 grades, the tensile strength of middle-thin fabric before washing is not less than 200 N, and the tear strength is not less than 6.5 N.