The compatibility between isotactic polypropylene (

i

PP) and ethylene-propylene-diene terpolymer (EPDM) in the blends was studied. SAXS analysis indicates that

i

PP and EPDM phases in the binary blend are incompatible. Isothermal crystallization behaviors of

i

PP in phase-separated iPP/EPDM were studied by

in situ

POM equipped with a Linkam shear hot stage. It was found that typical spherulites of

i

PP were formed both in neat

i

PP and in

i

PP/EPDM blends. The radial growth rate (d

R

/d

t

) of spherulites of

i

PP in the blend was not influenced by EPDM phases. Further investigations on isothermal crystallization of iPP in

i

PP/EPDM after shear with a fixed shear time showed that the crystallization rate of

i

PP in the blends increased with increasing shear rates

whereas

the crystallization rate was much lower than that of neat

i

PP. WAXD results showed that

β

-crystal

i

PP was formed in neat

i

PP as well as in

i

PP/EPDM blends after shearing and the percentage of

β

-crystal bore a relationship to the applied shear rate. The presence of EPDM resulted in lower percentage of

β

-crystal in the blends than that in neat

i

PP under the same constant shear conditions. SAXS experiments revealed that shear flow could induce formation of oriented lamellae in

i

PP and

i

PP in the blends

and the presence of EPDM led to a reduced fraction of oriented lamellae.