Calculation procedures for the connected double tubesheets is based on single tubesheet in current standards. Current situation, calculation methods and calculation procedures were introduced in this paper. Some options in calculation procedure for connected double tubesheets were not specified yet in standards and make engineers confused. It was point out that deformation features and stress levels in tubesheet can be qualitatively analyzed by means of two key constrain parameters m and K. The two Parameters are helpful to analyze the differences and relations between single tubesheet and double tubesheets in engineering design. Examples were calculated with different procedure options to compare with FEA after qualitatively analysis. The reasonability of different calculation procedures was discussed based on inner and outer tubesheet respectively. The preferences of procedure options were put forward to improve and perfect specification in current standards finally.