Abstract: On the basis of simply analyzing technical characters of least squares collocation, a general expression of experiential covariance function is put forward, which is identic for many gravity field variables of different types and above different heights. With the general expression, we can construct the same arithmetic for interpolation, extrapolation and continuation of local gravity field variables and estimation of different heights of theirs. Some arithmetic characters of least squares collocation are a a nalyzed and some problems are noted in arithmetic realization through testing. It is indicate that the resolution of inverse covariance matrix is not a key problem at all and the main mission is to study more efficient, more exact experiential covariance function for least squares collocation in local gravity field.