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Previous studies have reported that carrier-drug mass ratio has a significant influence on the aerosol performance of dry powder inhalation systems. This paper investigated the effect of carrier-drug mass ratio in different inhaler designs based on a multi-scale modelling technique combined computational fluid dynamics (CFD) and discrete element method (DEM) approach, aiming to develop better understanding of the aerosolisation mechanism of carrier-based formulation . Different formulations containing drug (salbutamol sulphate) and carrier (lactose) were used in experimental and numerical works with varied carrier-drug mass ratios ranging from 1:10 to 1:200. The fine particle fractions (FPFs) in the original and cross grid inhaler-throat model were measured to characterize the aerosolisation performance. The dynamics of the carrier particles in the original and cross grid inhaler-throat model were simulated. The experimental results showed that the significant difference between the original and cross-grid design for the pure drug but not for the carrier system. The numerical results showed that there was no much different in FPFs until a critical threshold was exceeded when the drug loading increased.