Rapeseed and mustard is most important oilseed crop in Pakistan. Lack of genotypes with wide stability across environments has been one of the most important constraints of rapeseed and mustard production in the country. Field experiments were conducted at eight different locations in 2018-19 and 2019-2020, in order to estimate seed yield stability. Eight advanced rapeseed genotypes were grown under randomized complete block design with 3 replications. Mean seed yield during 2018-19 range from 1891 to 2219 kg/ha. While mean seed yield during 2019-20 range from 1591 to 2016 kg/ha. Pooled analysis of variance showed highly significant differences among genotypes (G), locations (L), years (Y) and significant G x L, L x Y and G x L x Y interaction. However, G x L x Y interaction was greater than G x L and G x Y interaction so each location in each year was treated as separate environment. From this study it is concluded that the stable genotypes changes by changing the stability parameters used in computing stability analysis. For example during 2018-19, biplot drawn between CV (%) and seed yield (kg/ha) marked the RR-8-1 and RBN-13016 as stable genotypes while the biplot between b_i and S²di showed CHS-9 and RBN-13017 as the adaptable genotype in this period. In the same cropping season 2018-19 according to Eberhart and Russel (1966) method the genotype RBN-13016 was marked as the stable genotype over the location under study because it showed above average yield response and regression coefficient near to unity and has low value of S²d_i with high R²_i value.   Similarly during 2019-20, biplot drawn between CV (%) and seed yield (kg/ha) marked the RR-8-1 and CHS-9 as stable and good performing genotypes while the biplot between b_i and S²di showed none of the genotypes as stable or adaptable genotype in this period.  During the cropping season 2019-20 according to Eberhart and Russel (1966) genotypes RR-8-1 was found to be stable genotype over the location under study due to its above average yield response and regression coefficient near to unit with low value of S²d_i and high value of R²_i. Current study indicated that there is great genetic diversity among brassica genotypes under variable climatic conditions and this variation can be exploited in the future breeding programs in developing climate resilient high yielding varieties

Key words: Biplot, Brassica napus, Genetic Diversity,  Phenotypic Stability, Pooled Analysis of Variance, Regression Coefficient, Seed Yield,