Keith Brown will open the four-day event, which will be held virtually due to Covid-19, by calling on members to have "respectful, constructive discussions" with people who can be won around to the independence cause.
The call comes in the same week that First Minister Nicola Sturgeon announced work would be undertaken on a "prospectus" for an independent Scotland.
The recent deal between the SNP and Greens, which put the junior party's co-leaders into ministerial office, included a pledge to hold another referendum by the end of 2023.
Addressing SNP members, Mr Brown will say: "The case for independence cannot just be left to the Scottish Government. Every member of the SNP family knows we all have a crucial role to play.
"Our task is to convince those who do not yet support our cause. That means engaging in respectful, constructive discussions with those fellow Scots who remain open to persuasion.
"We must accept that, in 2014, many ordinary voters were cowed and confused by the scare tactics of Project Fear. We must accept that, even now, many of those same fears persist.
"So, we must listen to our hesitant fellow Scots and convince them by the power of our positive arguments that there is absolutely nothing to fear, that Scotland is big enough, is clever enough, rich enough, so long as we are bold enough."
He is expected to add: "Indeed, it will be our collective task to prove how the dangerous future for Scotland is, not through independence, but remaining in this dysfunctional Westminster system.
"So today I challenge each and every one of our supporters to reach out for indy.
"To redouble your efforts to convince at least one more undecided voter that the needs of the people of this country are best achieved as an independent nation.”
The speech will also come the day after a poll by Opinium for Sky News found that, of the 1,014 respondents, 51% wanted to see an independent Scotland, when all undecided voters were removed.