Multiple grayscales Gray code 3d measurement method was researched for the problems of two grayscales Gray code three dimensional measurement method which are more coding patterns and low measuring ef- ficiency. The method used multiple grayscales to form coding patterns

and can effectively to reduce the numbers of coding pattern

significantly improve the measurement efficiency under the same conditions compared with two grayscales Gray code method. The measured space is divided into Nmregions through m N （N∈Z

N≥3 ）grayscales Gray code patterns

the stripes in coded patterns are parallel

and the widths of the stripes are the same. N grayscales gray code is converted to N-nary number according to Gray code coded images

and then N-nary number is converted to decimal number

the corresponding region order in the coded patterns of each pixel in coded images can be obtained

and the 3d coordinates on the measured surface can be obtained by combined with the mathemati- cal model of optical triangulation. The experimental results show that variance of the plane whose depth distance is 850 N 1150 mm is less than 2 mm2

and measurement error is less than 2 mm

and maximum absolute error is less than 5 mm

this method is applicable to the measured object whose surface is complex and discontinuous

the measurement results can well reflect the details of the measured surface characteristics.