Different subsurface drainage scenarios including controlled drainage, subirrigation and conventional drainage were studied in a 52 ha. field in northern Iran paddy fields at Amol region using DRAINMOD. The soil texture in the site generally was loam in different layers. In model simulations, 30 year climatic data were used.In each case, different combinations of drain depth and spacing were simulated (drain depth of 1.5, 1.2, and 1.1m and drain spacing of 50, 40, and 30 m for conventional drainage, controlled drainage, and subirrigation, respectively). The results were investigated based on following 8 factors: sum of excess water (SEW), depth of water table, surface runoff, drainage volume, number of working days, relative yield, number of wet days and periods.To compare different scenarios, one combination of the drain depth and spacing was selected. The results showed that sub irrigation is not suitable because of high rainfall in the region. conventional controlled drainage system can be used for these fields, so that in wet season the system acts like a conventional or free drainage system and in paddy rice growh periods, it operates as controlled drainage by installing a weir setting in outlet drain. In all simulations, the excess soil moisture was the main factor for yield reduction and the best conditions of controlled drainage and subirrigation were obrained when the depth of weir setting was the same as Grain depth and these systems acted as conventional drains.