The determination of the structure of light harvesting complex Ⅱ and the development of ultrafast technique provide us the possibility to investigate the mechanisms in primary process of photosynthesis. Femtosecond (fs) pump probe technique at different wavelengths and time resolved photoluminescence technique (TRPL) were used to study photoinduced ultrafast dynamics processes in the LHCⅡisolated from the leaf of soybean. A mode locked Nd:YAG laser served as the excitation source in the TRPL measurements

and the excitation wavelength could be tuned from 570 nm to 610 nm with 10 ps pulse duration. The anisotropic dynamics were observed from TRPL spectra of LHCⅡ at different temperature

indicating that the energy transfer among pigments is affected by temperature. In the femtosecond pump probe measurements

Ti:sapphire laser and an optical parametric amplifier (OPA)were used as excitation source to generate tunable infrared laser pulses at wavelength from 1.1μm to 1.4μm. By using a YCOB crystal

second harmonic beam at visible light was obtained to be applied as the laser source in our measurements

which could be tuned from 550 nm to 700 nm with 150 fs pulse duration and 1 kHz repetition rate. From the femtosecond dynamical results

it could be observed the energy transfer processes between Chl a Chl b and Chl a Chl a pigments at different sites. The dynamical traces demonstrated that the energy relaxation from Chl b to its neighboring Chl a takes place in 200～300fs time region

the excitation relaxation between the excitonic states of Chl a in several hundreds of femtoseconds

and the energy equilibrium process of intermolecular of Chl a in several picoseconds. The observed slower decay component with the time constant up to hundred picoseconds from time resolved fluorescence and femtosecond dynamics traces could be assigned to the change of molecular conformation or energy equilibrium in LHCⅡ. These results have some significance in understanding the photophysical and photochemical mechanism in primary process of photosynthesis.