Simplifying transmission in a distributed parallel computing system. The method includes: identifying at least one item in a data input to the parallel computing unit; creating a correspondence relation between the at least one item and indices thereof according to a simplification coding algorithm, where the average size of the indices is less than the average size of the at least one item; replacing the at least one item with the corresponding indices according to the correspondence relation; generating simplified intermediate results by the parallel computing unit based on the indices; and transmitting the simplified intermediate results. The invention also provides a system corresponding to the above method.