The Scot, who has spent the winter adjusting her technique under new coach Malcolm Arnold, took first place in the 400 metres hurdles in 58.96 seconds ahead of Ese Okoro.
And she will now set her sights on the Grand Prix circuit and closing in on her rivals.
Child said: "I have to aim to be in the top 12 at the worlds. I want to lower my PB because I didn't lower that as much as I should have last year. I want a time that reflects my training."
Scotland team-mate Andy Frost broke his personal best in the hammer with a throw of 72.79m while James Campbell won the javelin in 75.03m.
Jade Nimmo produced a brilliant long jump of 6.31m while Lee McConnell was second in the 200m.