This　paper　studies　the　attitude　tracking　control　problem　of　the　rigid　spacecraft　with　parametric　uncertainties　and　unknown　bounded　disturbances.　Firstly,　an　ideal　generalized　predictive　controller　(GPC)　containing　unknown　items　is　constructed,　which　can　optimize　the　receding　horizon　performance　index　and　ensure　the　optimal　performance　of　the　closed-loop　system.　Afterward,　in　an　attempt　to　estimate　and　compensate　the　lump　model　uncertainties,　an　extended　state　observer　is　proposed　by　using　the　hyperbolic　tangent　function.　Meanwhile,　the　explicit　tuning　rules　for　observer　parameters　are　derived　on　account　of　the　stability　analysis.　And　then,　it　is　fully　proved　in　Lyapunov　framework　that　all　closed-loop　signals　invariably　keep　bounded　and　the　attitude　tracking　error　ultimately　converges　to　a　little　neighborhood　of　zero.　Lastly,　the　simulation　results　show　the　high　efficiency　and　precision　of　the　proposed　control　method.　(C)　2020　COSPAR.　Published　by　Elsevier　Ltd.　All　rights　reserved.