需要添加 {NSBaselineOffsetAttributeName : @0}

NSMutableAttributedString *attStr = [[NSMutableAttributedString alloc] initWithString:@"市場價："];
    [attStr appendAttributedString:[[NSAttributedString alloc] initWithString:[NSString stringWithFormat:@"￥ %@", _goodDetailModel.goodsMarketPrice] attributes:@{NSStrikethroughStyleAttributeName : @(NSUnderlinePatternSolid | NSUnderlineStyleSingle), NSBaselineOffsetAttributeName : @0}]];
marketPriceLabel.attributedText = attStr;