Expressing the sediment yield of the watershed as a factor of watershed characteristics is important to avoid the continual measurement of sediments in the watershed. The study investigates the effects of watershed characteristics on Sediment Yield by using GIS and Principal Component Analysis (PCA) in the case of four sub watersheds in Tana sub basin, Northern Ethiopia. The objective of the study is to identify the most principal factors which affect Sediment Yield for the four selected sub watershed by correlation and multiple linear regression. The Sediment Yield of each watershed was estimated in the study area and the relationship of the watershed characteristics and Sediment Yield was developed. This thesis used about 28 factors that affect the watershed property and then determining which factors that may affect the Sediment Yield as dependent variable in the study using principal component analysis. Factors that affect the watershed characteristics included in the thesis were Area(A), Perimeter(P), Circular ratio(Cr), Form factor(Ff), Max Discharge(MQ), Average Discharge(AQ), Longest flow path(Lfp), Drainage density(Dd), Total Stream Length(TSL), Max. Daily Rainfall(MDRF), Total Seasonal Rainfall(TSRF), Slope(S), Hypsometric Integral(HI), Relief ratio(Rr), Basin relief(Br), Ruggedness number(Rn), Elongation ratio(Er), Stream frequency(Sf), Average Elevation(Ave.E), Luvisols(Luv), Cambisols(Cam), Vertisols(Ver), Nitosols(Nit), Lithosols(Lit), Average Suspended Sediment Concentration(ASSC), Forest(FC), Non-Cultivated Land(NCL) and Cultivated Land (CL). The Suspended Sediment Yield of the watersheds was 31.5, 20.2, 34.9 and 36.2 tone/hac/season for the study area Tikur-Wuha, Guale, Enkulal and Tomma watersheds respectively. The most principal factor which determine Sediment Yield includes, NVC, TSRF, TLS, HI, Br, Rr, Rn, Dd, MDRF, VC, P, ASSC, A, Nit, Lit, FC and Ave.E using SPSS. While using multiple linear regressions the Forest Coverage of watershed, Stream Frequency and Hypsometric Integral are the factors that affect Suspended Sediment Yield. To minimize the sediment loss of the watershed the communities should have to practice reforestation and buffering the land surface from cattle’s and grassing. While for the other two factors conservation structures like stone / earth terracing and gully control structures. Key words: Sediment Yield; Principal Component Analysis; Geographical Information System;