A　parameterized　design　of　speed　servo　controller　for　brushless　DC　motors　is　presented　based　on　a　robust　composite　nonlinear　control　framework.　The　servo　controller　consists　of　a　linear　control　part　for　achieving　fast　response,　a　nonlinear　feedback　part　for　suppressing　the　overshoot,　and　a　disturbance　compensation　mechanism　for　erasing　the　steady-state　error.　A　reduced-order　extended　state　observer　is　adopted　to　estimate　the　un-measurable　state　variables　and　unknown　disturbance.　Simulations　are　first　carried　out　in　MATLAB/Simulink,　followed　by　real-time　experiment　using　a　TMS320F28335　digital　signal　controller　board.　The　results　confirm　that　the　proposed　control　scheme　can　achieve　fast,　smooth　and　accurate　tracking　of　target　speed,　and　has　a　good　performance　robustness　against　the　load　disturbance　and　parameter　variations.