We propose a new method to calculate the tide riding water level only using the high and low tide data. Based on the tide table’s data of the high and low tide data and hourly tide level data from tidal stations of different tide types in China，we use the calculation results by the standard method to verify the results of this method，and analyze the calculation error from multiple aspects. The results show that most of the new method’s errors are within 10 cm，and the maximum error is about 20 cm in the area which is obviously impacted by runoff and shallow water tidal component. Thus，the results of the new method can meet the engineering requirements. This method has clear physical meaning，simple formula and can be easily solved by calculator or Excel software. This method can be used to calculate the tide riding water level in the sea area lacking hourly tide level data.