In tidal irrigation system, river water is supplied by gravity through the sluice gate for a few hours during high tide periods in fresh water zone. The study area is situated in Nyaungdon Township, Ayeyarwady Division. Tidal irrigation system of Pan Hlaing sluice was implemented at Pan Hlaing River since 1995. In this study, the irrigation system is reviewed whether it is still fit or not due to the impact of climate changes. At first, using ten years meteorological data (from 2009 to 2018), crop water requirements are calculated by CROPWAT 8.0 software based on Penman-Monteith Method. The crop water requirements get highest in March. Then the tidal curve is constructed based on high tide and low tide level in March. The number of openings of sluice is calculated by using irrigation time of tidal curve and maximum crop water requirement. The number of openings of the sluice is fifteen. The existing number of openings of the sluice is twenty five numbers. The irrigation canal and outfall channel are designed by using Manning’s formula. The result, as the crop water requirement and tidal irrigation time are more, the number of openings is less. The sluice is benefited about 17000 acres (70%) of summer paddy. Although calculated irrigation canal width is larger than the existing canal width, outfall channel width is less than the existing channel width.