改成这样

var price = document.getElementById('it');
var count = 1;
var total = 0;
var countEl = document.getElementById('count');
var countEl1 = document.getElementById('total');

$(document).ready(function() {
    $('#it').val($('input[checked]').val());
    $('#total').val($('input[checked]').val());

    $('input[type=radio]').click(function() {
        $('#it').val(this.value);
        $('#total').val($('#it').val()* count);
    });
});

$(function(){
    $('#it,#count').change(function(){
        $('#total').val((+$('#it').val() || 0) * (+$('#count').val() || 0));
    });
     $("input[type=radio]").click(function(){
        $("#it").val($(this).val()).change();
    });
    $('input[type=radio]:first').click();
})

没测，你试试。

先说一下，jq和原生的这种混写真是别扭
$(document).ready(function(){

    *$("#it").val($('input[type=radio]:checked').val());*
    $("input[type=radio]").click(function(){
        $("#it").val($(this).val());
    });
    var price = document.getElementById('it');
    var count = 1;
    var total =0;
    var countEl = document.getElementById("count");
    var countEl1 = document.getElementById("total");
    *countEl1.value = count * price.value;*
    function plus(){
        count++;
        total=price.value*count;
        countEl.value = count;
        countEl1.value = total;
    }
    function minus(){
        if (count > 1) {
            count--;
            total=price.value*count;
            countEl.value = count;
            countEl1.value = total;
        }
    }
});