The invention discloses an entropy theory based assembly contact stress distribution assessment method which includes the steps of firstly, building a measurement coordinate system and a three-dimensional solid model to a to-be-tested part, subjecting the three-dimensional solid model to finite element cell meshing, and calculating strain energy density of each cell; secondly, calculating the overall entropy estimate value, the overall maximum entropy, the overall normalized entropy value Hs according to the strain energy density of each cell; thirdly, judging whether Hs is greater than or equal to the set threshold value, if so, then taking Hs as an assessment index to assess assembly stress distribution uniformity of surfaces of the to-be-tested part, and if not, then going to the next step; fourthly, building multiple sections perpendicular to the Z-axis of the measurement coordinate system; fifthly, searching a section with convex hulls of which quantity and area accounting for the maximum ratio to the surface area of the to-be-tested part, and calculating the convex hull height entropy estimate value, the convex hull height maximum entropy, and the convex hull normalized entropy value Hcs; sixthly, building the assessment index Ec that is equal to AHS + BHCS; and finally assessing the assembly stress distribution uniformity of the surfaces of the to-be-tested part according to the assessment index Ec.