Perovskite light-emitting diodes (PeLEDs), owing to their unique photoelectric performance, show promising prospects in display applications. Red, green, and blue monochromatic PeLEDs have achieved remarkable breakthroughs, but the study of red/green/blue perovskite co-electroluminescence is still delayed. This study proposed a strategy that an intermediate connection layer (ICL) with hole/electron generation and transport capability is introduced between perovskites. On the one hand, introduction of the ICL can inhibit ion exchange and energy transfer. On the other hand, ICL has a charge-generation function that ensures different perovskite centers capture enough carriers. Furthermore, the thickness of the hole transport layer (NPB) is optimized. Furthermore, the thickness of the hole transport layer (NPB) is regulated, the blue/green tandem PeLED achieved relatively balanced luminescence and exhibits the largest EQE of 0.33%. The developed red/green/blue tandem PeLED exhibits the highest EQE of 0.5%, which is the first report in the field of PeLEDs, and exhibits the largest External Quantum Efficiency(EQE) of 0.33%. The developed red/green/blue tandem PeLED exhibits the highest EQE of 0.5%. In conclusion, this work provides a reference strategy for the co-electroluminescence of multicolor perovskites, which is expected to promote the development of perovskite in display applications.