At present, the underground and Open pit co-mining technologies has been applied to some coal areas in Quang Ninh coal basin for increasing the coal productivity , meeting the coal demands for domestic and export as well. However, for applying this method, it is necessary to carry out and solve the concerned problems and among them, the mutual effects in the mining activities are very important. The paper refers to the deformation effects in the flowsheet for underground and open pit co-mining technology with the numerical model.