Average ranges of recoil nuclides in the target materials induced by fast neutronreactions have been measured by the activation method. A systematic trend ofaverage range was found for (n

2n)

(n

a )

(n

p) and (n

np) reactions. An empiricalformula was presented to describe the experimental results. Moreover

the calculatedresults based on theoretical formula were compared with the experimental results. Arevised formula was deduced from the present work.