The ryanodine receptors (RyRs) are intracellular Ca²⁺ releasing channels on the sarcoplasmic reticulum membrane and play a pivotal role in the excitation-contraction coupling of skeletal and cardiac muscles as well as other physiological processes. With the recent development of Cryo-EM and the improvement of data analysis technique, scientists from China, the United States and Germany have acquired high-quality RyR1 images at the total resolutions of 3.8 Å (1 Å=10^-10 m), 4.8 Å and 6.1 Å, respectively, which have been published in the same issue of Nature in 2015. RyR1s are homotetrameric complexes with a molecular mass of more than 2200000, mainly containing a cytoplasmic region composed of NTD, SPRY, P1, P2, B-sol and C-sol domains and a channel region composed of S1-S6, VSL and CTD domains. As the most common factor affecting the condition of RyR1, Ca²⁺ is able to bind the EF-hand subdomain in the cytoplasmic region, which further causes the conformational change and finally leads to the channel opening.