Abstract: Toreducethecostandimprovethereliabilityofmicro-satellites，amethodwhichemployingmagnetictorquesastheonlyactuatorswasdevelopedtorealizethreeaxisstablecontrol.Thenbyusinglinearquadraticregulator（LQR）optimalcontroltheory，theinfinitetimestateregulatorandsteadygainregulatorweredesignedtostabilizemicro-satellitetonadirpointingusingfullymagnetictorques.Meanwhile，takingKaiTuo-1satellitein-orbitflightastheresearchobject，theproductofinertia，orbitinclination，residualmagnetismandaerodynamicdragdisturbancethatbringsdifferenteffectsforthecontrolprecisionwereanalyzed.SimulationresultsvalidateefficiencyandpracticabilityofLQRcontroller.Itcanachievehighcontrolprecisionunderlittledisturbance.

Key words: micro-satellite, 3-axisattitudestability, magneticcontrol, optimalcontrol, controlprecision