The invention provides a description model of fluctuation intervals of wave force amplitudes of a cylindrical array in a non-capture area, comprising the following steps: listing the velocity potential of water wave diffraction near any cylinder, the diffraction coefficient being determined by a linear equation set; Solving the linear equation set by adopting a Claimer rule to obtain a target square matrix determinant; Ignoring the quantity slowly changing along with the wave number in the square expression of the determinant model to obtain a target expression; Solving a first derivative of the expression and enabling the first derivative to be equal to zero to obtain a transcendental equation; And deducing a fluctuation interval expression of any cylindrical wave force amplitude curve byusing a transcendental equation, and performing synthesizing to obtain a description model of the non-capture region. The method has the advantages that the fluctuation interval of the wave force amplitude curve in the non-capture area is not changed along with the change of the dimensionless wave number and is only related to the total number of cylinders in the cylinder array, the number of thecolumns marking the positions of the cylinders and the wave incident angle, and accurate prediction can be realized by the aid of a formula provided by the invention.