  We present a simple method which simplifies the evaluation of the on-shell
multiple box diagrams reducing them to triangle type ones. For the $L$-loop
diagram one gets the expression in terms of Feynman parameters with $2L$-fold
integration. As examples we consider the 2 and 3 loops cases, the numerical
integration up to six loops is also presented. The method is valid in six
dimensions where neither UV not IR divergences appear.
