We investigate the role of the length scale of attraction on the dynamical heterogeneity in three dimensional core-softened (CS) model liquid having interaction potential of two different length scales. Using the simple CSmodel, we have shown that the presence of heterogeneity is attributed to the existence of attractive interactions in a system.The timescale associated with the peakposition of the non-Gaussian parameter is found to be strongly dependent on the temperature for different length scale of attraction.The dynamical heterogeneity dramatically decreases with the increase in temperature. We further characterize dynamical heterogeneity by calculating newnon-Gaussian parameter which indicates the existence of much longer relaxation timescale than that suggested by the peak position in the non-Gaussian parameter. Furthermore, we have shown the presence of particles, whose displacement distribution deviates from the Gaussian distribution and contributes towards the origin/presence of heterogeneity.