The phase structure and morphology of polypropylene (,i,PP) blends with poly(decamethylene sebacamide (polyamide 1010, PA1010) and the part-compatible alloys (,i,PP/PA1010/,i,PP-,g,-MAH) are investigated by Rayleigh scattering,i.e., small angle light scattering (SALS). The structure parameters of SALS,i.e., correlation distance,a,c, and average chord lengths,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=34326366&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=34326376&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=34326371&type=, are calculated. Their variation with the composition of the blends and alloys is discussed. The morphology and structure of fracture surfaces in the blends and alloys are studied by SEM images. The average diameter of dispersed phase in the blends and alloys is calculated by graph processing. The variation of average diameter is similar as that of average chord lengths of dispersed phases. The mechanical properties of the blends and alloys are analyzed and the relation of modulus and yield stress with the composition is studied. It is confirmed that the correlation between the modulus and the structure parameters is non-linear, while the correlation between the yield stress and the composition or structure parameters is linear.