The invention relates to a substituted 2-aminopyridine compound and a preparation method and application thereof, in particular to derivatives of 5 ((R) 1 (2,6 dichloro 3 fluorophenyl)ethyoxyl) 4' methoxy 6' ((S) 2 methylpiperazin 1 yl) 3,3' bipyridyl 6 amine and a preparation method and application thereof. The high-purity substituted 2-aminopyridine compound can effectively improve scientificityand accuracy of detection of 5 ((R) 1 (2,6 dichloro 3 fluorophenyl)ethyoxyl) 4' methoxy 6' ((S) 2 methylpiperazin 1 yl) 3,3' bipyridyl 6 amine citrate and impurities of preparations thereof, and theimpurity content of the compound and preparations thereof can be effectively and conveniently monitored to facilitate the control of the quality of the compound and the preparations thereof, so that the safety and effectiveness of the compound and the preparations thereof are ensured.