Abstract: In order to improve the accuracy and reliability of the measured depth transfer of a standard well,the measured depths of many standard wells were transferred to a new standard well.On the basis of unequal precision of the data delivered by different standard wells,transfer results were weighted according to the error degree of each pass to calculate the best estimate of collar depth by weighted average method.Through drawing the probability density curve of standard collar depth measurements,the degree of error of processing the results between the weighted average method and direct average method was calculated to analyze the credibility of the transfer results.Analysis showed that,on the probability density curve of standard collar depth measurements,the position of depth value transferred by multi wells was close to the maximum probability density.However,the transferred depth value of a single well was largely deviated.The results of analysis showed that the transmission reliability of multiple wells was higher than a single well.The error of calculation processing results showed,the credibility of the best estimate of weighted average method was higher than the direct average method.Altogether,using the measured depths transfer from the multi depth standard well to new standard well and calculating the best estimate of collar depth value by the weighted average method could improve the precision and reliability of the measured depth transfer of the standard well.