Thanks, I knew it. I mean the "Statistic" page.
From my understanding, this balance update is based on the total of rewards in past one hour.
but for each reward, it's quite less than my calculation. I also asked the other's rewards, their rewards match this kind of formulate:
(my shares contributed)/(all shares contributed) *50 *93(7)%, obviously mine is not.
btw, I also noticed the number of "last 24 hours" on statistic page, mine is 1.32BTC, he has 1.8BTC, we have almost same rate, mine is 1.7G~1.8G, he has 1.7G.