In order to enhance the legumes potential advantages on the cereal yield in intercropping system by nitrogen direct transfer from legume to cereal, an intercropping experiment was conducted between eight maize varieties (07SADVE, 08SADVE 1, 09SADVE F2, Mudishi 1, Mudishi 3, VP0523, ZM538 and Samaru), cowpea (Vigna unguiculata var. H4) and soybean (Glycine max var. Vuangi) during November 2011-February 2012 season at INERA/Mvuazi in the south-western country of DR Congo. The experimental design was a Split plot with four replications, twenty six treatments were applied between maize varieties monocrops (40.000 plant·ha^﹣1) and legumes in monoculture (360.000 plant·ha^﹣1) and both of sole planting were combined. Evaluation of these soles planting was performed on basis of several intercropping indices (MYE, LER, ATER, RCC, A and CR), the monetary advantage index (MAI), Actual Yield Loss index (AYL) and intercropping index (IA). After data analysis, competitivity indices indicated the higher yields advantages of maize varieties in intercropping, especially Mudishi 3-soybean (MYE = 2836.300 kg·ha^﹣1). The equivalent land ratio (LER) varied with 08SADVE 1variety between 0.70 and 1.66 in cowpea and soybean intercrops respectively, the Relative crowding coefficient (RCC) showed yield advantage of all intercrops except with 09SADVE F2, Mudishi 1 and 07SADVE. Aggressivity (A) showed dominance of maize in all intercrops, against the Competitive ratio (CR) showed that the competitivity was stronger on cowpea (from 16.42 to 98.63) than soybean (from 16.12 to 25.70). Actual yield loss (AYL) was negative in all intercrops with cowpea and soybean. Thus, the index of association (IA) informed that the negative values of the different intercrops were due to the maize price (1000 CDF·kg^﹣1) and legumes price (1500 CDF·kg^﹣1). Finally, the monetary advantage index (MAI = 922.92) and PCA had determined that intercrop with Mudishi 3-soybean as an economic efficiency intercrop than others mixtures.