Using imported “Rubbia” colour pepper as test material,longshort row space 70 cm-40 cm,and plant space 45 cm(double planting),35 cm(double planting),30 cm(single planting),20 cm(single planting) 4 levels were set,effect of different planting densities on the yield in greenhouses were studied.The results showed that a planting space of 35 cm×70 cm-40 cm was obtained the highest yield in greenhouses in Xining region,with the significant difference of other densities,doule planting obtained relative high yield,the ideal planting density was 6 000～7 000 plants per 667 m2.