In order to improve domestic-made XBT fall rate equation（ FRE）

use method based on image processing to measure movement parameters of XBT probe. Difference image is obtained by background difference method

appropriate threshold is selected and binaryzation of difference image is carried out

connected region of binary image is labeled and binary image is divided into several independent regions. The XBT probe is recognized by calculating and analyzing characteristic set of each connected region. Motion posture of probe is described by central axis of probe

long axis of XBT probe used as initial central axis of probe

and iterative optimization method is used to get more precise results. The experimental results show that average error of angle measurement is less than 0. 5° and the algorithm satisfies precision requirement of posture measurement of XBT probe. Vision measurement system based on this algorithm has been applied in XBT deployment experiments and results are satisfied.