Owing to the growing demand for ubiquitous connectivity, low earth orbit (LEO) satellite-based communication networks are envisioned as a key-enabling technology for the next-generation networks. However, the existing literature disregards the heterogeneous nature of the real-world LEO satellite networks. Motivated by this, in this paper, an analytical framework based on stochastic geometry is developed, aiming to assess the downlink coverage performance of the large-scale heterogeneous LEO satellite-based communication networks. Based on the proposed mathematical framework, we derive the analytical expressions for the coverage probability, by taking into account the existence of inter-cell interference. Our results show that the inter-cell interference and fading channels jeopardize the coverage performance. Moreover, increasing the transmit power can improve the coverage probability at the low signal-to-noise ratio regime. Finally, we demonstrate that a higher coverage probability is achieved by narrowing the beam and/or by lowering the altitude of the LEO satellites.