The Manusina raced out to a 17-0 lead inside the first 20 minutes in Lautoka, against a Hong Kong team which had convincingly defeated Fiji at the weekend.
Lock Apaula Kerisiano Enesi, debutant hooker Eta Mailau and fullback Soteria Pulumu scored tries for Samoa.
Co-captain Marilyn Live also found the tryline as Samoa went into half-time with a commanding 22-0 lead.
Hong Kong fought back in the second spell with three tries but substitute Ta'imua Taiao and a second from fullback Pulumu sealed a convincing Samoan victory against the 2017 World Cup attendees.