Abstract: The failure pattern of composite foundation with cement treated column of 18 meters long in soft soil,and the effect of sand cushion and strength of pile on it’s bearing capacity are studied by conducting field loading tests of single pile,on single pile with cap and four piles with cap and with or without sand cushion,and on single pile with cap and with a steel tube in the pile. Some suggestion to the loading test and the determination of bearing capacity of composite foundation with long cement treated column in soft soil are given.