A method of nuclear emission time scale based on analysing kinematics of sequential decay fragments has been established. Directions of eastted trajectories are varied with Coulomb interaction between fragments. The shapes of the relative angle correlation functions symmetric ternary fission for example

are changed with take difference τof emission

where τis a free parameter ranging from 0 to 2000fm/c. It is shown that the time scale reduces

with the increase of excitation energy for Ar+Au reactions

from ～1000fm/c at 25MeV/u to 50-100fm/c at 60MeV/u

and the mode of decay evolves from sequential to prompt.