For the problem that the calculation formula of anti-overturning stability of concrete interlocking blocks does not consider the influence of water depth in the standard formula，the stress of concrete interlocking blocks underwater current is studied，and new calculation formula of anti-lifting stability of concrete interlocking blocks is obtained by theoretical deduction method，then the relevant parameters of the new formula are determined by combining mathematical model analysis. In the new formula，the influence of water depth is considered，and the critical current velocity at the edge of the soft mattress is replaced by the average current velocity of the critical section，which is more accurate than the standard formula. In this paper，new formulas and standard formulas are respectively adopted to calculate the anti-overturning stability of bottom protection soft mattresses of the Heishazhou channel regulation project Phase II. The analysis results show that the new formulas can better reflect the actual force of soft mattresses than the standard formulas. Engineering practice proves that the new formulas have better reliability and can be used for reference of similar projects.