The original description of Sinotyrannus proposed that it could have been the earliest tyrannosaurid due to its large size, but subsequent analyses place it as a proceratosaurid tyrannosauroid.
It is considered to be part of a clade containing Juratyrant and Stokesosaurus, as they all reputedly share a narrow preacetabular notch.
A 2016 analysis instead placed Juratyrant and Stokesosaurus outside of proceratosauridae and proposed that Sinotyrannus is a sister taxon of Yutyrannus within proceratosauridae.

Below is a cladogram by Loewen et al.
in 2013.
The original description of Sinotyrannus proposed that it could have been the earliest tyrannosaurid due to its large size, but subsequent analyses place it as a proceratosaurid tyrannosauroid. It is considered to be part of a clade containing Juratyrant and Stokesosaurus, as they all reputedly share a narrow preacetabular notch. A 2016 analysis instead placed Juratyrant and Stokesosaurus outside of proceratosauridae and proposed that Sinotyrannus is a sister taxon of Yutyrannus within proceratosauridae.
Below is a cladogram by Loewen et al. in 2013.
Sinotyrannus