Peatland is a potential land farming for increasing food abundance. This study aimed to determine the effect of ameliorants (sea water, volcanic ash, zeolite and CaCO3) to improvement of Toba Highlands Peatlands chemical properties. This research used factorial complete randomized design with two factor treatments consist of ameliorant application and washing frequency, with four combination those are (A0) Sea water, (A1) volcanic dust plus sea water, (A2) zeolite plus sea water, (A3) CaCO3+ sea water with 2 replications The results showed that application of ameliorant influenced significantly to increase soil pH, electric conductivity, carbon organic, N total, K-exchangeble and Ca-exchangeble. The frequency of washing increase of soil pH significantly