Influences of remanent magnetization on dynamic magnetomechanical mechanisms in a bi-layer asymmetric magnetoelectric (ME) laminate consisting of lead zirconate titanate and samarium iron alloy has been studied systematically, and the underlying hysteresis physics involved in dynamic magnetomechanical process as well as its magnetic-sensing characteristics was intensively characterized. To appreciate the distinct magnetostriction and ferromagnetism simultaneously in samarium iron alloy, key magnetomechanical parameters of dynamic piezomagnetic coefficient, Young's modulus and mechanical quality factors exhibit hysteresis behaviors under magnetic field application. Consequently, high sensitivity in proposed bi-payer laminate for field detection can be reached without the facilitation of additional bias field. Experimental results show that the ME output has an approximately linear correlation with the applied AC magnetic field, and the low-frequency and the detection limits at 1 kHz and 120 kHz can reach 2.3 × 10−6 T and 2.2 × 10−8 T, respectively. These unique features provide such an asymmetric ME composite great potentials for weak magnetic field detection without DC bias field.