The measurement of the spectacles frame parameters has substantial effects on both the production and ex- port of spectacles products.In fact,this measurement is the measurement of related three-dimensional trajectory. The working principles of the measurement apparatus developed based on capacitive grating technology are introduced in this paper.Capacitive grating technology is a precision length measurement method.Its advantages are small vol- ume,low price,low production cost,and easy to obtain precise readings of the measured data.The measurement apparatus is composed of one industrial control computer,two microcontrollers and corresponding circuits.The sys- tem stability is guaranteed during the design of the circuit with the practical situation of its industry application taken into account.The software is divided into lower layer and upper layer.Each layer has different emphasis.The cau- ses of system errors and the method of error elimination are also analyzed.The analysis of the data obtained from ex- periments and the operating results of prototype apparatus both indicate that the proposed measurement apparatus has achieved outstanding competitive technical level of same kind products in international market and thus has ideal im- plications for mass production. The measurement of the spectacles frame parameters has substantial effects on both the production and ex- port of spectacles products. Fact, this measurement is the measurement of related three-dimensional trajectory. The working principles of the measurement apparatus developed based on capacitive grating technology are introduced in this paper. Positive grating technology is a precision length measurement method. Its advantages are small vol ume, low price, low production cost, and easy to obtain precise readings of the measured data. The measurement apparatus is composed of one industrial control computer, two microcontrollers and corresponding circuits. the sys- tem stability is guaranteed during the design of the circuit with the practical situation of its industry application taken into account. software is divided into lower layer and upper layer. The cau- ses of system errors and the method of error elimination are also analyzed. The analysis of t he data obtained from ex-periments and the operating results of prototype apparatus both indicate that the proposed measurement apparatus has achieved outstanding competitive technical level of same kind products in international market and has had ideal im- plications for mass production.