We report the effect of Ca doping in $YBa<_2$$Cu_3$O／sub 7－$delta$／ (YBCO) thin films grown on the Rolling- Assisted, Biaxially Textured Substrates (RABiTS) with the architecture of $CeO_2$／YSZ／CEO$_2$／Ni. Critical currents of bilayer and trilayer structures of YBCO／Y／sub 0.7／Ca／sub 0.3／$Ba_2$$Cu_3$O／sub 7－$delta$／ (YCaBCO) as well as undoped YBCO for comparison have been measured in a wide range of temperatures and fields. For $6－8^{circ}$ grain boundaries, 30% Ca-doping in bilayer structure enhances Jc as high as 35 %. The enhancement is larger at low temperatures and at magnetic fields. On the other hand, 30% Ca-doping in trilayer structure reduces Jc as high as 60%. Combined with slightly lower Tc, this indicates that Ca is overdoped in this structure and degrades GBs.