Hu also signed a five-year free trade pact on Friday with General Pervez Musharraf, the Pakistani president, which is expected to triple trade to $15bn.
Beijing has maintained a close relationship by helping Islamabad build nuclear power plants and a deep-sea port.
China helped Pakistan set up a nuclear power plant in the 1990s.
The aviation deals involve the Pakistan Air Force and CETC, a Chinese aviation company, working together on China's airborne early warning system.
Another Chinese company, CATIC, will deliver the first eight JF-17 Thunder fighter aircraft jointly developed with Pakistan.