The diagnostic of DT fuel plasma areal density in the direct-driven implosion experiments on SG-Ⅱ laser facility has been performed by measuring the number of recoil D and T produced by 14MeV neutron′s scattering. The particles of recoil D and T were detected by CR39 solid-state nuclear track detector. The experimental results indicate that the uniformity of laser illuminating affects the compression to a certain extent. The areal density of exploding pusher target is about one order lower than that of ablative-driven target. This means that the compression of ablative-driven target is better than exploding pusher target. There is a strong relationship between areal density and suprathermal electron heating.