Abstract: To help the designers to rationally select proper design specifications for calculating the sloshing wave height of stored liquid in steel welded storage tank under different conditions, this paper presents the computational formulae and influential factors of sloshing wave height in such tank design specifications as GB 50341-2003, GB 50761-2012 and API 650-2013, and mainly analyzes the effects of basic stored liquid sloshing cycle on the value of seismic influence factor in GB 50341-2003 and GB 50761-2012 and their differences. Moreover, calculation is made on basic stored liquid sloshing cycle, seismic influence factor and stored liquid sloshing wave height of 10×10⁴ m³, 1×10⁴ m³ and 200 m³ storage tanks, respectively. The calculation results show that the basic sloshing cycles of storage tanks with the same volume and diameter-height ratio are identical, however, the greater the diameter-height ratio, the more different the sloshing wave height figured out as per GB 50761-2012, API 650-2013 and GB 50341-2003 is, when the diameter-height ratio tends to be 1, the sloshing wave heights figured out as per GB 50761-2012, API 650-2013 and GB 50341-2003 are only slightly different. Finally, based on comparison and analyses on the calculation results, this paper presents the applicability of sloshing wave height computational formulae in the tank design specifications.