A peakingfree disturbance observerbased slidingmode guidance law (PDOBSMG) is proposed for the homing missile in the presence of maneuvering targets. A peakingfree disturbance observer (PDOB) is firstly proposed to estimate the unknown target acceleration, which preserves the estimation accuracy as well as eliminates the peaking phenomenon of the existing disturbance observer. Then a PDOBSMG is designed based on the estimated target acceleration of PDOB. For the existing disturbance observerbased sliding mode guidance law (DOSMG), the guidance performance may be negatively affected by the initial peaking phenomenon. With the help of peakingfree feature of PDOB, the problem caused by the initial peaking is solved by the proposed PDOBSMG. Finally, simulation comparison results are provided to demonstrate the effectiveness of the proposed methods.