The invention discloses a method for calculating a coefficient of any order in a neutron transport discrete nodal method. The method mainly comprises the steps of 1, performing form simplification: performing form simplification on complex source coefficient, flux coefficient and coupling coefficient by introducing an intermediate coefficient; 2, performing integral transformation: transforming an integral, appearing in the source coefficient, the flux coefficient and the coupling coefficient, of an exponential function and Legendre polynomial product into an integral of the exponential function and general polynomial product according to properties of a Legendre polynomial; and 3, performing analytic solving: analytically deriving accurate expressions and recursive relations of an intermediate integral through a mathematic method, substituting an intermediate integral value accurately solved by a computer into expressions of the source coefficient, the flux coefficient and the coupling coefficient after integral transformation, and obtaining accurate values of the source coefficient, the flux coefficient and the coupling coefficient of any order in combination with an intermediate coefficient value as a known condition, wherein the accurate expressions and the recursive relations do not contain complex integral operations and are easily realized by computer programming.