Abstract: During the embankment construction of the Dong yi\|dao's viaduct bridge of Ninghuai expressway, there was the field test to study the effect of reinforced earth in reducing the earth pressure of abutment. Test results showed that the distribution of earth pressure along the height of abutment is not smooth quadratic curve, but rather an irregular S\|shaped curve. In order to eliminate various factors effect on test accuracy in construction field and find out reasons of measurement error, it is suggest that is expressed as increase of earth pressure changes with the filling height.