He started practicing Muay Thai in at the age of 12 with his brothers in a camp close to his home.

Nongkhai won his Lumpinee Stadium debut by knockout in the second round but later lost on points at Rajadamnern Stadium which led him to return to the northeastern region for 2 years using the ring name "Nongkhai Amornrat" (หนองคาย อมรรัตน์).

[1] 1974 was the breakout year for Nongkhai in January he beat a Kung Fu specialist by knockout in the first round, this fight brought a lot of attention and Nongkhai went on a 9 fights winning streak before losing to Ruengsak Porntawee.

[2] During the second half of 1970s Nongkhai fought the best fighters of his era and registered notable wins against Samersing Tianhirun, Khunponnoi Kiatsuriya, Jitti Kiatsuriya, Narongnoi Kiatbandit, Sagat Petchyindee, Vicharnnoi Porntawee, Pudpadnoi Worawut, Kaopong Sitichuchai, Ruengsak Porntawee, Padejsuk Pitsanurachan At the peak of his career he received purses of 250,000 baht.

[3] He was chosen as the 130 lbs Thai representant for the World Martial Fesstyle Championship of 1982 in which he won the belt by knocking out his japanese opponent, Kunimasa Nagae, in the final.