Design optimization of oilfield development is the most effective means for improving the intrinsic safety of oil and gas production facilities and design quality has direct effect on operation of these facilities. In Tazhong No. 1 Gas Filed west block development， in order to reduce safety risk likely resulted from design reason and eliminate potential operation accident hazards in design stage， analyzed are some problems exposed in single well trial production design and applied is man-machine engineering to describe risks likely resulted from such problems and proposed are some improvement suggestions. Through the implementation of subsequent design， good effects have been achieved， operation risks are reduced and intrinsic safety is improved accordingly. Therefore， single well design analysis， which is based on man-machine engineering， is very necessary for improving intrinsic safety.