The temporal evolution of laser-induced zinc plasma during its spatia l expansion and the dependence of plasma formation on laser energy have been ext ensively studied using laser induced breakdown spectroscopy.A pulsed laser is u sed to ablate the zinc metal target to generate plasma in air conditions.The ti me-resolved plasma fluorescence spectra at different positions along the direct i on of the plasma expansion are collected and the plasma characteristic parameter s are determined to study the spatial expansion and temporal evolution of plasma .The influence of laser energy on plasma formation is studied by changing the l aser energy.The spectral line intensity,electron temperature,electron number density parameters and their temporal evolution at different pulse energies are determined.The early expansion process of plasma is a supersonic adiabatic expa nsion process,the electron temperature first decreases and then increases with the spatial expansion of the plasma,while the electron number density first inc reases and then decreases.With the increase of delay time (~2.2μs),the electro n temperature decreases continuously with the increase of space distance,while the electron number density remains almost unchanged,the supersonic adiabatic e xpansion process vanishes.With the increase of laser pulse energy,the characte ristic line intensity of zinc gradually saturates,the increase rate of electron number density gradually reduces and the lifetime of plasma continuously increa ses.When the laser energy is lower than 100mJ,the electron temperature of pla sma rapidly increase with laser pulse energy,when the laser energy becomes larg er than 100mJ,the electron temperature saturates around 8500K and no longer i ncreases.The results show that the plasma shielding effect becomes obvious with the increase of laser energy,the plasma generated in the early stage absorbs l aser energy to maintain its existence and only part of the laser energy can inte ract with the metal target,the threshold of spectral line intensity and electro n temperature are reached.