Due to the variousness and the complexity of the geological conditions and the observation environments of a pit

it is unavoidable for model errors to exist in the data processing model of pit displacement monitoring.If they are significant

the result will be of poor precision and the successive deformation analysis will be incorrect.The problem is discussed deeply in the paper

and a new method to process the pit displacement monitoring data considering the model errors is put foreword

which is based on the theories of least squares collocation and robust estimation.The relative formulae are then derived in detail.At last

with several examples

it is proved effective in improving the precision of the displacement estimation model

i.e.

the precision improvement rate is at a scale of 35%～48%.