Large samples of quasars were discovered at z~6 and higher during the last decade. These objects provide the best targets to study the growth of supermassive black holes (SMBH) and their connections to galaxy formation at the reionization era. Huge amount of dust and molecular gas were detected in about 30% of the luminous quasars at z~6, which suggests an early phase of SMBH-galaxy evolution with massive star formation. The star formation rates estimated with the FIR dust continuum emission are about a few hundred to a thousand Msun/yr. Observations using the large submillimeter/millimeter and radio telescopes, such as ALMA and the JVLA, directly probe the distribution of star formation and dynamical properties of the atomic/molecular gas in these young quasar host galaxies. In this talk, I will summarize the most recent millimeter and radio observations of the z~6 quasars and discuss how the results constrain the co-evolution of SMBHs and their host galaxies at the earliest epoch.