Collinear dual pulse laser-induced breakdown spectroscopy with and without cavity confinement were carried out on a Si crystal sample by using two Nd : YAG laser sources emitting at 1064 nm and a 1 mm-height and 3 mm diameter aluminum cylindrical cavity. Nearly 2–3 times enhanced optical emission intensity with a higher signal-to-noise ratio was observed when an additional cylindrical cavity was used to confine the laser plasma. The inter-pulse delay time to achieve the maximum atomic and ionic line intensity was optimized for both confined and unconfined collinear dual pulse laser plasma, and a modest difference of the optimized inter-pulse delay time was found. Based on the relative standard deviation of several selected Si line intensities, it was ascertained that the signal intensity from confined collinear dual laser plasma emission showed a better stability. Plasma temperature and electron number density of confined collinear dual pulse laser plasma was measured and compared with that of unconfined laser plasma as well.